When I was writing the book that became Conjuration, I kept careful track of my citations from the various libraries I visited and online resources used over the several years I spent gathering my information. Then, when I was ready to print the book -- I felt like an idiot when I discovered a few of my citations were either missing or improperly recorded! I ended up making a note in the bibliography about that matter, that there might be a few things where the citations couldn't be found... instead of having to delay the book in hopes that the might eventually be rediscovered.
I'm happy to report that today I came across the note for one of those lost citations! I had mentioned in the book that sigils had been used in African magic since at least the year 1800, but couldn't seem to find my source on that. I finally happened upon a note I scrawled down on a paper that apparently got separated from the rest of my notes -- "1800, 'A Treatise on Sugar' Benjamin Moseley - sigils."
Moseley didn't have the nicest things to say about black people or their magical practices, but that doesn't make his reports of those practices that were happening in his own era and which he could see with his own eyes any less valuable. Here's his mention of the use of sigils:
Many of their wayward visitors were deeply skilled in magic and what we call the black art which they brought with them from Africa and in return for their accommodation they usually taught their landlord the mysteries of sigils spells and sorcery and illuminated him in all the occult science of OBI.
The new printing of the book, Conjuration: Hoodoo Spells from 1800 to 1920 has amended the bibliography.