C. D. Broad 
Lectures on Psychical Research (Routledge Revivals) [PDF ebook] 
Incorporating the Perrott Lectures Given in Cambridge University in 1959 and 1960

This book, first published in 1962, is based on a series of lectures first given at Cambridge University in 1959 and 1960, dealing with ”psychical research” – i.e. the scientific investigation of ostensibly paranormal phenomena. Split into three sections, Professor Broad”s study examines numerous issues relating to psychical theory, including guessing, hallucinatory quasi-perception and trance-mediumship.