| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Ufo Directory: A Guide to Organizations, Research Collections, Museums, Publications, Periodicals, Web Sites, and Other Resources Concerning Ufo Phenomena | 978-0-7808-0289-6 (0-7808-0289-6) | 1999 |
| UFO Encyclopedia 2nd | 978-0-7808-0097-7 (0-7808-0097-4) | 1998 |
C C · C. Clark · J C · J. Clark · Jerome Clark