I found out that the Encyclopedic Course in Occultism by Gregory Ottonovich Mebes, mentioned in Mouni Sadhu's The Tarot, a Guide to the Quintessence of Hermetic Occultism, had actually been published in book form, instead of merely being circulated in a select circle of adepts. It was published in 1913, in Russian, and therefore in the old orthography.
This led me to be curious about what a Russian typewriter keyboard looked like under the old orthography...
The top three keyboards show the evolution of the Russian typewriter keyboard; the bottom two, the Bulgarian.
G. O. Mebes also wrote the second half of the book, on the Minor Arcana - it was published in a Portuguese translation in Brazil after his notes were smuggled out of Russia. G. O. Mebes himself perished in a Soviet labor camp.