Swap Clubs Author:William Breedlove An early study of Wife Swap Clubs before it became popular and in the common stream of publications. Over 400 couples were interviewed and reported. A good read!
An book on the early beginnings of "Key Clubs", "Swinging", and "wife swapping". This has grown to "Sharing", "Cuckolding", "Life Style", etc. If you want to get the flavor of the early days of "coming out" I recommend this book.