Bathgate, Michael R. The Shapeshifter Fox: The Imagery of Transformation and the Transformation of Imagery in Japanese Religion and Folklore. Chicago: The University of Chicago, June 2001. Doctoral thesis.
Blacker, Carmen. The Catalpa Bow: A Study of Japanese Shamanistic Practices. Routledge Curzon, 1999.
A thorough description of Japanese shamanism that includes an entire chapter on magical animals, including kitsune.
Davis, Winston. Dojo: Magic and Exorcism in Modern Japan. Stanford: Stanford University Press, 1980.
A study of the Sukyo Mahikari sect, a religion that believes in possession by spirit animals and the dead. The author describes several cases of fox possession and exorcism. Link