UFOS AND RELATED SUBJECTS: AN ANNOTATED BIBLIOGRAPHY BY LYNN E. CATOE, LIBRARY OF CONGRESS, DEFENSE TECHNICAL INFORMATION CENTER (1969)
THE INVISIBLE COLLEGE: WHAT A GROUP OF SCIENTISTS HAS DISCOVERED ABOUT UFO INFLUENCE ON THE HUMAN RACE BY JACQUES F. VALLÉE (1975)
SUPERNATURAL RELIGION : AN INQUIRY INTO THE REALITY OF DIVINE REVELATION BY WALTER RICHARD CASSELS (1874)
THE EDGE OF REALITY: A PROGRESS REPORT ON UNIDENTIFIED FLYING OBJECTS BY J. ALLEN HYNEK, JACQUES VALLEE (1975)