We've read most of these but we're putting all of them here so that we have a reference list for the ones we haven't got to yet. Feel free to have a browse for these but some are out of print so can be very difficult to get hold of. Any we find on the internet will have a clickable link.
They are in many different subjects and written by many influential people. If you have any suggestions for this list, please let us know. We're always looking for more!
2012 Science and the Afterlife Experience (Chris Carter)
2011 Soul Dust: The Magic of Consciousness (Nick Humphreys)
2010 Paranormality (Dr Richard Wiseman)
2009 The Accidental Census (Romer and Smith)
2006 Our Haunted Lives (Jeff Belanger)
2003 Records in Stone (Clive Ruggles)
2002 Seeing Ghosts (Dr Hilary Evans)
2001 The Sagas of Icelanders (Various: Penguin Classics)
1998 Forbidden Archaeology (Michael Cremo and Richard Thompson)
1997 Reincarnation and Biology (Ian Stevenson)
1996 The Limits of Influence: Psychokinesis and the Philosophy of Science (Stephen Baude)
1979 Poltergeists (Gauld and Cornell)
1975 Life After Life: The Investigation of a Phenomena (Raymond Moody)
1967 Megalithic Sites in Britain (Prof. Alexander Thom)
1956 Six Theories on Apparitions (Prof. Hornell Hart)
1948 Mass Observation Survey (DJ West)
1943 Apparitions (GNM Tyrrell)
1927 Megalithic Sites in Britain (Prof. Alexander Thom)
1920 An Encyclopaedia of Occultism (Lewis Spence)
1894 Census of Hallucinations (Society of Psychical Research)
1882 The Road To Immortality (F.W.H. Myers)
1640 Foras Feasa ar Eireann History of Ireland (Prof. Geoffrey Keating)
1572 Of Ghosts and Spirits Walking By Nyght (Lewes Laveter)
1550's Ystoria Taliesin, a document covering the writings of the 6th Century Bard.
1270's (approx) Cōdex Rēgius (Unknown)
An online compendium of esoteric writings of various time periods can be found here, including the rare De Septum Secundies by Johannes Trithemius and even rarer Tabula Bonorum Angelorum Invocationes by Dr John Dee.