Much like Rue I most of what I do was spirit taught, or I learn it as a small child from my mentor. But I was lucky enough to be able to study folklore and magical practices academically back in college, so even if it hasn't effected my practice a ton, I do have a standing bibliography. So some of my favorites include:
Ioan Myrddin Lewis. Ecstatic Religion. Routledge, 1971.
Kieckhefer, Richard, and Bayerische Staatsbibliothek. Forbidden Rites : A Necromancer’s Manual of the Fifteenth Century /. Stroud, Sutton, 1997.
Lecouteux, Claude. Demons and Spirits of the Land. Simon and Schuster, 17 July 2015.
---. The Tradition of Household Spirits. Simon and Schuster, 21 July 2013.
Morton, Lisa. Calling the Spirits : A History of Seances. London Reaktion Books, 2020.
Ostling, Michael, and Springerlink (Online Service. Fairies, Demons, and Nature Spirits : “Small Gods” at the Margins of Christendom. London, Palgrave Macmillan Uk, 2018.
Pratt, Christina. An Encyclopedia of Shamanism
. Vol 1 & 2. New York Rosen Publ. Group, 2007.
Tomlinson, Matt. Speaking with the Dead. punctum books, 2024.
Wilby, Emma. Cunning Folk and Familiar Spirits. Liverpool University Press, 2005.
I also have a treasure trove of journal articles. You can make a Jstor account for free and search for key terms like witchcraft, spirit medium, or mediumship and get some great stuff. I also recommend the ethnographer Jack Hunter. I was clearly not the right audience for his work, so I was super bored when I tried one of his books. He was speaking to a reader who was new to both spirit work and anthropological research - I heave experience with both - but his books would probably be a great jumping off point for someone else.
I also highly highly recommend researching your spirits domains. I read a lot of books about fungi, death, and funerary practices because 1) I'm into those subjects and 2) learning about them helps me understand Brona better. I read about historical hunting practices to understand Oisin. I've learned stone knapping to understand Flint, sailing for Pesse, etc. Researching for spirit work doesn't stop at books about spirit work techniques, or even books about types of spirits. Anything that helps you connect and relate to your spirits better is research for your spirit work.
And I can't over state this enough. No amount of what I think of as "literature review" - the book research, the bibliography building - can replace the field research of actually doing spirit work. You can read a million books and articles, watch hours of videos, listen to months of podcasts. None of it really matters until you put the knowledge you gained into action.
*A note of the word "shamanism." The academic field of anthropology has some gross history with this word. There are sadly some great resources out there that use the term as a catch all for "indigenous spiritual practice that involves spirit work, otherworldly travel, and spirit healing." Most often this catch all is only used in the title for categorization/SEO purposes and then an appropriate term from the culture being discussed is used in the actual body of the work. Anthropologist are doing better and leaving the gross history of the field behind, but nothing in academia is fixed quickly. Just an FYI.