If you're looking for a collection of easy-to-read one page stories about the mysterious and paranormal, you'll enjoy this. However, if you're looking to do some serious research on these subjects, you'll have to look elsewhere. There are no footnotes or sources, no index, no bibliography. The stories could be made up for all the reader can tell.
Today, the internet can help track down the truth (or fiction) of many of these stories, but back in the 1960s, 70s and 80s there were literally hundreds of books like this rushed out to satisfy public demand, and they aren't worth much to the serious scholar.