Imprimātur is Latin for “let it be printed”. The term has been widely used by the Catholic Church in two senses: a) in old times, for authorizing the publication of a book, otherwise to be censored; b) in modern times, as an endorsement of the contents of a book, stating they represent the view of the Church. The Imprimātur must be issued by a proper Authority from the Church.
In A∴A∴, the Imprimātur is used as a way to issue certain writings as official instructions of the Order, and in most of the cases it also assigns a number and a class to that instruction.
An official instruction of A∴A∴ usually is called a liber, Latin for “book”, and its plural form is librī, “books”.
Most of the librī of A∴A∴ and O.T.O. are assigned to a Roman number:
- Liber III vel Jugorum.
- Liber Trigrammaton sub figūra XXVII.
- Liber CCCXXXV, Adonis.
“Title sub figūra x” is Latin for “Title under the number x”.
Those numbers do not follow a sequential order: A Note on Genesis is attributed to the number MMCMXI (2911), but it is not the 2911ᵗʰ official instruction of A∴A∴.
Actually the numbers are chosen as a reference to the nature of the liber itself:
- Liber III vel Jugorum: “III. Refers to the threefold method given, and to the Triangle as a binding force.”
- Liber Trigrammaton sub figūra XXVII: “XXVII. The number of permutations of 3 things taken 3 at a time, and (of course) the cube of 3.”
- Liber CCCXXXV, Adonis: “CCCXXXV. The Numeration of Adonis in Greek.”
In The Equinox Vol. I No. 10 Crowley explains the A∴A∴ classification system:
The publications of the A∴A∴ divide themselves into four classes.
Class “A” consists of books of which may be changed not so much as the style of a letter: that is, they represent the utterance of an Adept entirely beyond the criticism of even the Visible Head of the Organization.
Class “B” consists of books or essays which are the result of ordinary scholarship, enlightened and earnest.
Class “C” consists of matter which is to be regarded rather as suggestive than anything else.
Class “D” consists of the Official Rituals and Instructions.
Some publications are composite, and pertain to more than one class.
In 1919, Crowley started to issue Class “E” publications:
Class “E” consists of public announcements and broadsheets.
The Three Chiefs
When the A∴A∴ was founded, It inherited the three ruling offices from its predecessor Order, the Hermetic Order of the Golden Dawn. Such offices are explained in the Ritual of the Neophyte of the H.O.G.D. as published in The Equinox Vol I. No. 2:
At the East of the Temple before Paroketh sit the three Chiefs who govern and rule all things and are the viceroys in the Temple of the Second Order beyond. They are the reflections therein of the 7°=4°, 6°=5°, and 5°=6° Grades, and are neither comprehended in, nor understood by, the Outer Order. They represent, as it were, Veiled Divinities […]
Now the Imperator governeth, because in Netzach — which is the highest grade of the First Order — is the fire reflected from Geburah.
The Praemonstrator is second, because in Hod is the water reflected from Chesed.
The Cancellarius is third, because in Yesod is the air reflected from Tiphereth.
But in each Temple these three chiefs are coeternal and coequal, thus figuring the Triad in Unity, yet are their functions different:
The Imperator to command
The Praemonstrator to instruct.
The Cancellarius to record.
Other functions are mentioned, for example: Chancellor (see the first pages of The Equinox Vol. I Nos. 7-10), Praemonstrātor-General (see Book Four Parts 1 and 2), and Grand-Neophyte (see One Star in Sight), but we do not have much information on them.
Certain librī list officers in the Imprimātur page, others don’t.
At the time A∴A∴ was founded, these were the three chiefs of the Order, ruling from the Collēgiō Internō (Inner College) and authorizing all official instructions:
- Frater D.D.S., George Cecil Jones, as the Praemonstrātor. He was an Adeptus Exemptus 7○=4□.
- Frater O.M., Aleister Crowley, as the Imperātor. He was a newly formed Magister Templi 8○=3□, however, since the office of Imperātor is attributed to Geburah, his 6○=5□ motto is listed.
- Frater N.S.F., John Frederick Charles Fuller, as the Cancellārius. He was only a Probationer 0○=0□, but in order to serve as the Cancellārius, he received an honorary 5○=6□.
Eventually Jones and Fuller withdrew from A∴A∴ and Crowley became the sole leader. Crowley still regarded Jones as Praemonstrātor in later years, but Fuller was completely disregarded:
“The Chancellor of the A∴A∴ wishes to warn readers of The Equinox against accepting instruction in his name from an ex-Probationer, Captain J. F. C. Fuller, whose motto was ‘Per Ardua.’ This person never advanced beyond the Degree of Probationer, never sent in a record, and has presumably neither performed practices nor obtained results. He has not, and never has had, authority to give instructions in the name of the A∴A∴.”
In 1919, a new governing triad was announced in The Equinox Vol. III No. 1. Now the Chiefs were chosen from the External College (prō Collēgiō Externō):
- Frater V.N., George Cecil Jones, as the Praemonstrātor.
- Frater P., Aleister Crowley, as the Imperātor.
- Frater Achad, Charles Stansfeld Jones, as the Cancellārius.
Note that these are all magickal mottos for Grades below Tiphereth.
George Cecil Jones was no longer involved with A∴A∴ since around 1911, but Crowley still recognized him as the source of instruction.
As far as 1936 (The Equinox of the Gods), this was the governing Triad of A∴A∴, although Charles Stansfeld Jones was no longer active in A∴A∴ and even joined the Roman Catholic Church in 1928. In 1936 he was officially expelled from the O.T.O. after starting to publicly attack Crowley and Thelema.
In July 18, 1941, Crowley appointed Karl J. Gemer as his representative:
“All persons in authority under me in connection with the A∴A∴ and O.T.O. are to recognize him as their chief.”
After Crowley’s death in 1947, Gemer never organized a new governing triad.
Years after Germer’s death in 1962, different A∴A∴ claimant groups emerged, and they formed their own governing triads. One governing triad has no power over the others. Their authority reaches as far as their line of succession goes, or as far as their students recognize them as chiefs.
The Three Colleges
Usually the Imprimatur is issued from the Second Order (Collegio Interno), but there are also instances including authorities from the Third Order and even officers from the First Order:
- Collēgiō Summō, “highest college”, the Third Order, from 8○=3□ to 10○=1□.
- Collēgiō Internō, “inner college”, the Second Order, from 5○=6□ to 7○=4□.
- Collēgiō Externō, “external college”, the First Order, from 0○=0□ to 4○=7□.
Thus, for example, where we read “Pro. Col. Sum.” (prō Collēgiō Summō) it is meant “on behalf of the Highest College”.
The Seal of A∴A∴
Around 1912, the Seal of A∴A∴ was designed and published for the first time in Book Four Part I (Liber ABA, Part 1: Meditation). Its Seal was only going to figure as part of the Imprimātur page on 1919, with the release of The Equinox Vol. III No. 1.
The Egyptian Portal Cover
The Egyptian portal figuring as the cover of many A∴A∴ librī was designed in 1909, figuring in the privately printed volumes of ΘΕΛΗΜΑ, composed by most of the Holy Books of Thelema. However, the portal design only became public with the release of The Equinox Vol. III No. 1 in 1919. See the images below, the 1909 portal on the left and the 1919 portal on the right:
The Egyptian hieroglyphs at the bottom of the cover came from the Stele of Revealing:
|Bread and Wine||[Hadit] the Great God, the Lord of Heaven||Beef and Fowl|
N. Fra. A∴A∴
At times when no governing triad was formed, Crowley employed the “N. Fra. A∴A∴” as the authority for an Imprimātur. Let’s consider some information regarding that obscure authority:
- “N. Fra. A∴A∴” is only used when the governing triad is not complete.
- However, sometimes even with no triad the motto of the Imperātor stands alone, there is no “N. Fra. A∴A∴”.
- Book Four Parts 1 & 2 display “N. ·.· Praemonstrātor General”
- The Book of the Lies displays “Imprimatur [new line] N. [new line] Fra∴ A∴A∴”.
- Liber Astarté vel Berylli (Imprimatur: “N. Fra A∴A∴”) has a single footnote, attributed to one called “N. Fra. A∴A∴.”
- Liber HAD and Liber NV have “N. Fra A∴A∴” between “V.V.V.V.V. …” (a 8○=3□) and “O.M. 7○=4□”.
- In a footnote in Book Four, Part I, Chapter X: The Lamp, we have: “NEMO is the Master of the Temple, whose task it is to develop the beginner. See Liber CDXVIII, Æthyr XIII.”
- In the commentary to the 49ᵗʰ chapter of The Book of the Lies, we have: “NO MAN is of course NEMO, the Master of the Temple, Liber 418 will explain most of the allusions in this chapter.”
- In Liber 418, Æthyr XIII, we have multiple references to Nemo, such as “No man hath beheld the face of my Father. Therefore he that hath beheld it is called NEMO. And know thou that every man that is called NEMO hath a garden that he tendeth”, with the following footnote “Every Magister Templi has a Work to do for the world.”.
Considering these, N. Fra. A∴A∴ seems to mean “Nemo, Frater of A∴A∴”, Nemo being a generic term for a Magister Templi, in this case Aleister Crowley.
List of Authorities
These are the persons behind the mottoes found in the Imprimātur pages across the years. Each A∴A∴ claimant group has its own group of authorities filling the three offices. Thus a publication that got an Imprimātur from one A∴A∴ claimant group governing triad does not necessarily is an official publication for another A∴A∴ claimant group.
Please note that:
a) This list only includes names found in Imprimātur pages in published books. There are many other A∴A∴ claimant groups out there.
b) I do not vouch for the authenticity of these grade claims. Some of these people may have worked the grades of A∴A∴ by themselves.
c) Some of these grades are clearly honorary, they do not mean actual attainment in the proper Sephirah.
|George Cecil Jones||V.N.||Volo Noscere||I wish to know||[First Order]|
|George Cecil Jones||D.D.S.||[unknown]||[unknown]||7○=4□|
|John Frederick Charles Fuller||P.A.||Per Ardua||Through difficulties||[0○=0□]|
|John Frederick Charles Fuller||N.S.F||Non Sine Fulmine||Not without a thunderbolt||5○=6□ [honorary]|
|Aleister Crowley||P.||Perdurabo||I will endure||[First Order]|
|Aleister Crowley||O.S.V.||Ol Sonuf Vaoresagi||I reign over ye||6○=5□|
|Aleister Crowley||O.M.||ΟΥ̓ ΜΉ||Not||7○=4□|
|Aleister Crowley||V.V.V.V.V.||Vi Veri Universum Vivus Vici||By the power of truth, I, while living, have conquered the universe||8○=3□|
|Aleister Crowley||666||Τὸ Μέγα Θηρίον||The great beast||9○=2□|
|Charles Stansfeld Jones||-||Achad||Unity||[1○=10□]|
|Charles Stansfeld Jones||-||Parzival||-||5○=6□ [honorary]|
|Charles Stansfeld Jones||777||Omnia in Uno Unus in Omnibus||All in one, one in all||8○=3□|
|Allan Bennett||I.A.||Iehi Aour||Let there be light||5○=6□|
|Martha Küntzel||I.W.E.||Ich will es||I will it||7○=4□|
|Aiwass||93||[gematria for Hebrew עיוז]||-||10○=1□|
|[Nuit and Hadit]||-||Gods||-|
|[Aleister Crowley]||N. ·.·||[Nemo]||[Nobody; no one; no man]||[8○=3□]|
|[Seems to be used when the governing triad isn’t complete]||N. Fra: A∴A∴||[Nēmō Frater A∴A∴]||[Nemo, a Brother of A∴A∴]||[Third Order]|
|A∴A∴ via Crowley > Germer|
|Marcelo Ramos Motta||216||[gematria for Hebrew הוהר]||Ever||8○=3□|
|Marcelo Ramos Motta||Φ||[Greek letter phi, no point used as abbreviation]||[unknown]||6○=5□|
|Marcelo Ramos Motta||A.||Adjuvo||I will help||3○=8□|
|A∴A∴ via Crowley > Germer > Motta (a)|
|Mônica D. Rocha||EAEA||[unknown]||[unknown]||2○=9□|
|A∴A∴ via Crowley > Germer > Motta (b)|
|James Daniel Gunther||V.||[unknown]||[unknown]||7○=4□|
|[William Gary Keith Breeze]||V.V.||Veritas Vincit1||Truth prevails||6○=5□|
|[Martin Patrick Starr]||S.U.A.||[unknown]||[unknown]||5○=6□|
|A∴A∴ via Crowley > Germer > Motta (c)|
|Euclydes Lacerda de Almeida||M∴||Mohadib||[unknown]||2○=9□|
|A∴A∴ via Crowley > Germer / Wolfe (a)|
|James Arthur Eshelman||Π.||Προμηθεύς||Prometheus2||7○=4□|
|Phyllis Evalina Seckler||M.||Meral||I will to love||6○=5□|
|Anna-Kria King||S.e.S.||Sano et Sancto||I heal and make holy||5○=6□|
|A∴A∴ via Crowley > Germer / Wolfe (b)|
|[unknown, but definitely not the same V.V. as the above]||V.V.||[unknown]||[unknown]||6○=5□|
|David Shoemaker||I.||[unknown]||[unknown]||[First Order]|
|Joshua Gadbois||R.O.||[unknown]||[unknown]||[First Order]|
|A∴A∴ via Crowley > Germer / Wolfe (b) > Seckler|
|Grady Louis McMurtry||H.A.||[unknown]||[unknown]||8○=3□|
|A∴A∴ via Crowley > Germer / Wolfe (b) > Seckler > McMurtry|
|A∴A∴ via Crowley > Regardie > Suster|
We have representatives from three separate colleges here, plus O.S.V. as Imperātor. Curiously the offices of Cancellārius and Praemonstrātor are not indicated.
1909, The Equinox , Vol. I, No. 1, An Account of A∴A∴.
We have the three chiefs with their Grades. Their offices are not indicated.
1909, The Equinox , Vol. I, No. 1, Liber Exercitiorum.
Now we have the chiefs and their respective functions:
1909, The Equinox , Vol. I, No. 2, Liber O vel Manus et Sagittae.
In this sample the Grades are omitted; we only have the offices:
1910, The Equinox , Vol. I, No. 4, Liber III vel Jugorum.
Here the word “Imprimātur” is used:
1910, Liber Collegii Sancti.
This book was privately printed. In the photo below, we can see Crowley’s handwriting, probably revision marks to guide the editor for including it in The Equinox, Vol. III, No. 2, a book which was announced, but never released. Here Equinox No. 1 actually refers to The Equinox Vol. III No. 1, and in the page 100 is found the Imprimātur for De Lege Libellum.
1911, The Equinox , Vol. I, No. 5, Liber HHH.
After George Cecil Jones and John F. C. Fuller quitted A∴A∴, Crowley used the expression “N. Fra A∴A∴” and variations to indicate that no governing triad issued the publication.
1912, Liber ABA, Book Four, Part 1.
Here we have a curious variation that makes us speculate about the meaning of “N. Fra A∴A∴”. Clearly we have someone named “N. ·.·” who has the office of a “Praemonstrātor General”. Giving the many references to “Nemo” as a generic name for a Magister Templi, it may be possible that this “N. ·.·” is “Nemo ·.·”.
1912, The Equinox, Vol. I, No. 7, Liber NV.
Liber NV and Liber HAD have this peculiar Imprimātur, where we have the Egyptian hieroglyphs for “the gods”, followed by V.V.V.V.V. (Aleister Crowley’s 8 ○=3□ motto and/or the Chief of A∴A∴), N. Fra A∴A∴ (mostly used when no governing triad exists) and O.M. (Aleister Crowley’s 7○=4□ motto).
1913, The Book of Lies.
This seems to be a hybrid of Book Four’s “N. ·.·” and the “N. Fra A∴A∴” found in The Equinox:
1919, The Equinox, Vol. III, No. 1, Liber II.
Now we finally have a new governing triad in A∴A∴ and representants from all three colleges, but the chiefs operate from the External College, not from the Inner College as in 1909. Note that George Cecil Jones, long gone, is still referred to as the Praemonstrātor.
1929, Magick in Theory and Practice.
Book Four Part 3, Magick in Theory and Practice, has no Imprimātur page. It includes appendices with the main official instructions issued by A∴A∴, most of them published in The Equinox, but none of them include an Imprimātur.
1936, The Equinox of the Gods.
Here D.D.S. (George Cecil Jones) was replaced by I.W.E. (Martha Küntzel) in the Inner College, but he remains as V.N. and as Praemonstrātor in the External College.
1938, The Heart of the Master.
Once again we do not have a governing triad, we only have the Imperātor O.S.V., as we had in 1909.
1938, Little Essays Towards Truth.
Once again, a governing triad is not listed, only the Imperātor O.S.V., as in 1909.
1939, Eight Lectures on Yoga.
Once again, a governing triad is not listed, only the Imperātor O.S.V., as in 1909.
1944, The Equinox, Vol. III, No. 5, The Book of Thoth.
Curiously here we have two mottoes listed as members of the R.R. et A.C., the second order of the old Hermetic Order of the Golden Dawn. Allan Bennett was one of Crowley’s teachers in H.O.G.D., but he was dead and he has never been a member of Crowley’s A∴A∴.
1961, The Equinox, Vol. III, No. 6, Liber Aleph: The Book of Wisdom or Folly, edited by Marcelo Ramos Motta.
This is the first number of The Equinox released after Crowley’s death, in a partnership between Karl Germer and his student Marcelo Motta. This book was edited and printed in Brazil, and sold in USA.
Germer never entitled Motta as the Imperātor of A∴A∴, but at the time of the release of the book Motta sent letters to Germer claiming to be a 6 ○=5□ in another plane, the grade corresponding to the office of Imperātor.
1975, The Equinox , Vol. V, No. 1, The Commentaries of AL, by Marcelo Ramos Motta.
This is a new volume of The Equinox prepared by Marcelo Ramos Motta thirteen years after Karl Germer’s death. it does not list the officers, but we have mottoes of Marcelo Ramos Motta spanning the three colleges.
1979, The Equinox , Vol. V, No. 2, by Marcelo Ramos Motta.
1980, The Equinox , Vol. V, No. 3: The Chinese Texts of Magick and Mysticism, by Marcelo Ramos Motta.
1981, The Equinox , Vol. V, No. 4: Sex and Religion, by Marcelo Ramos Motta.
Required: Magick Without Tears Unexpurgated Commented Part 1
Do you have the first edition of this book? Please send us a picture of the Imprimātur page.
1984, Magick Without Tears Unexpurgated Commented Part 2, by Marcelo Ramos Motta.
After issuing the four numbers of his new volume of The Equinox, Motta fallbacks to the usage of “N. Frater A∴A∴”.
1987, Thelemic Magick Unexpurgated Commented Part 1, by Marcelo Ramos Motta.
This is the last Imprimātur issued by Motta:
1987, [Brazil] A Deusa Negra, by Euclydes Lacerda de Almeida.
Here we have an Imprimātur in the name of an organization, Horus-Maat Lodge.
1996, The Equinox , Vol. IV, No. 1: Commentaries on the Holy Books and Other Papers, by J. Daniel Gunther et al, Liber Vesta.
Nine years after Motta’s death, three of his ex-students, all of them who resigned or were cut contact with from Motta’s instruction in A∴A∴ while he was still alive, formed a new governing triad for their A∴A∴ claimant group:
1998, The Equinox , Vol. IV, No. 2: The Vision and the Voice with Commentaries and Other Papers, by J. Daniel Gunther et al.
Here we have the same governing triads, with no grades or colleges:
2000, The Mystical and Magickal System of A∴A∴ (3ʳᵈ Revised Edition), by James A. Eshelman: One Star in Sight.
Here we have three people from second order rankings and “N. Fra. A∴A∴”:
2009, Magick Revised, by Ray Eales.
2009, Initiation in the Aeon of the Child, by J. Daniel Gunther.
In his solo book, the Praemonstrātor of one of the claimant groups above listed himself as in “R.R. et A.C.” plus “N. Fra: A∴A∴”, as Crowley did in his last years.
2014, The Angel & The Abyss, by J. Daniel Gunther.
2014, Private publications, by The Hell Fire Club
2017, Winds of Wisdom, by David Shoemaker.
Here we have three officers in the External College, representants in the Inner College, and the exquisite “N. Fra. A∴A∴” in the Highest College.
2019, [Serbia] Anatomija Ambisa, by Dušan Trajković
2020 (TBR), [Brazil] Liber ABA, by Aleister Crowley, Commented by Marcelo Ramos Motta: Liber AL vel Legis.
I would like to thank all the people who provided information for this article: Scott Wilde, Vitor Campos, Erica Cornellius, David Shoemaker, Diego Zangado, Dušan Trajković, Minnie Pax, Robert Flores.
CROWLEY, Aleister. ΘΕΛΗΜΑ. London: Self-Published, 1909.
CROWLEY, Aleister. Book Four, Part I, Meditation. South Kensington: Wieland & Co., 1912.
CROWLEY, Aleister. Book Four, Part II, Magick: Preliminary Remarks. South Kensington: Wieland & Co., 1913.
CROWLEY, Aleister. Liber Collegii Sancti. London: self-published, 1910.
CROWLEY, Aleister. The Book of Lies. South Kensington: Wieland & Co., 1913.
CROWLEY, Aleister. Magick in Theory and Practice, being Book Four, Part III. Paris: The Lecram Press, 1929.
CROWLEY, Aleister. The Equinox of the Gods, being Book Four, Part IV; and The Equinox Volume III Number 3. London: Privately published, 1936.
CROWLEY, Aleister. The Heart of the Master. London: Privately published, 1938.
CROWLEY, Aleister. The Book of Thoth, being The Equinox Volume III Number 5. London: Privately published, 1944.
CROWLEY, Aleister. Liber Aleph: The Book of Wisdom or Folly, being The Equinox Volume III Number 6. West Point: Thelema Publishing Company, 1961.
CROWLEY, Aleister; et al. The Equinox Volume I Number 1. London: Simpkin, Marshall, Hamilton, Kent & CO. LTD., 1909
CROWLEY, Aleister; et al. The Equinox Volume I Number 2. London: Simpkin, Marshall, Hamilton, Kent & CO. LTD., 1909.
CROWLEY, Aleister; et al. The Equinox Volume I Number 3. London: Simpkin, Marshall, Hamilton, Kent & CO. LTD., 1910.
CROWLEY, Aleister; et al. The Equinox Volume I Number 4. London: self-published, 1910.
CROWLEY, Aleister; et al. The Equinox Volume I Number 5. London: self-published, 1911.
CROWLEY, Aleister; et al. The Equinox Volume I Number 6. London: Wieland & Co., 1911.
CROWLEY, Aleister; et al. The Equinox Volume I Number 7. London: Wieland & Co., 1912.
CROWLEY, Aleister; et al. The Equinox Volume I Number 8. London: Wieland & Co., 1912.
CROWLEY, Aleister; et al. The Equinox Volume I Number 9. London: Wieland & Co., 1913.
CROWLEY, Aleister; et al. The Equinox Volume I Number 10. London: Wieland & Co., 1913.
CROWLEY, Aleister; et al. The Equinox Volume III Number 1. Detroit: Universal Publishing Company, 1919.
CROWLEY, Aleister; et al. Commentaries on the Holy Books and Other Papers, being The Equinox Volume IV Number 1. York Beach: Samuel Weiser, 1996.
CROWLEY, Aleister; et al. The Vision and the Voice with Commentaries and Other Papers, being The Equinox Volume IV Number 2. York Beach: Samuel Weiser, 1998.
CROWLEY, Aleister; MOTTA, Marcelo Ramos. The Commentaries of AL, being The Equinox Volume V Number 1. New York: Samuel Weiser, 1975.
CROWLEY, Aleister; MOTTA, Marcelo Ramos. The Equinox Volume V Number 2. Nashville: Thelema Publishing Company, 1979.
CROWLEY, Aleister; MOTTA, Marcelo Ramos. The Equinox Volume V Number 3: The Chinese Texts of Magick and Mysticism. Nashville: Thelema Publishing Company, 1980.
CROWLEY, Aleister; MOTTA, Marcelo Ramos. The Equinox Volume V Number 4: Sex and Religion. Nashville: Thelema Publishing Company, 1981.
CROWLEY, Aleister; MOTTA, Marcelo Ramos. Magick Without Tears Unexpurgated Commented Part 2, being The Oriflamme Volume VI Number 4. Society Ordo Templi Orientis, 1984.
CROWLEY, Aleister; MOTTA, Marcelo Ramos. Thelemic Magick Unexpurgated Commented Part 1, being The Oriflamme Volume VI Number 5. Rio de Janeiro: Society Ordo Templi Orientis, 1987.
ESHELMAN, James A. The Mystical and Magickal System of A∴A∴. College of Thelema: 2000.
Explanation of Egyptian Art around Liber. Available at: <http://www.heruraha.net/viewtopic.php?f=4&t=4752>. Accessed on: Feb. 4ᵗʰ 2019.
Imprimatur. Available at: <https://www.merriam-webster.com/dictionary/imprimatur>. Accessed on: February 4ᵗʰ 2019.
Plus the books listed above.