It was my recent pleasure to obtain a copy of The Seen and The Unseen, A study of presences, apparitions, and other paranormal phenomena, by Society of Psychical Research council member Andrew MacKenzie. This book provides a collection of cases of apparitions that have been thoroughly investigated by a senior member of the SPR, and found to be at the very least intriguing. The beginning of the book is devoted to the sense of presences both positive and negative, something the author feels has been somewhat neglected by psychical research. The bulk of the book consists of cases of hauntings including the visual sighting of apparitions, and poltergeist phenomena. The book sums up the evidence gathered from the cases presented, relates them to other data collected world over, and examines the state of psychical research along with considerations for the future. This is an older book (first published in 1987) but refreshingly I found it highly relevant to today, and do recommend it to any serious student of psychical research or parapsychology.
The Seen and the Unseen, by Andrew Mackenzie, Publishers: Weidenfeld and Nicolson (c) 1987 ISBN 0 297 79045 5