"Thirty Years Among the Dead" is a well-known book by Dr. Carl Wickland originally published in 1924.
The book recounts Dr. Wickland's efforts to cure his psychiatric patients by spiritualist methods. His wife Anna was a powerful medium, and Wickland became convinced that some of the incurable patients institutionalised at his facility were suffering from spirit obsession. He tested his theory by subjecting the patients to electroshock therapy, which was intended to drive the obsessing entity out of the patient's "magnetic aura." The entity was then attracted to the entranced Mrs. Wickland. Dr. Wickland would speak with the earthbound spirit in an attempt to convince the spirit to open his or her spiritual eyes and progress to the next stage of development. In many cases the effort proved successful, and the patient, who had previously resisted all cures, improved markedly and could be de-institutionalised.
No doubt "Thirty Years Among the Dead" is a classic in paranormal research and abnormal psychology.