CREATURES FROM THE INNER SPHERE by F.W. Holiday

A cut above the Chariots, a work of cracked genius. Recommended.

Popular Library, 1973

THE DEVIL'S TRIANGLE by Richard Winer

Spends some time in the final chapter taking John Wallace Spencer and others to task for spreading Triangle hokum. Winer himself is not above some good scare mongering as can be seen in the copy excerpt and dedication.

Bantam Books, 1974

MAPS OF THE UNKNOWN: Dragons of the Loughs

From Creatures From the Inner Sphere, by F.W. Holiday. Courtesy Popular Library, 1973.

FLYING SAUCERS: THE STARTLING EVIDENCE OF THE INVASION FROM OUTER SPACE by Coral Lorenzen

Available to read and download at archive dot org.

Signet Books, 1966

THE MYSTERIOUS MONSTERS by Robert and Frances Guenette

A thorough little volume that names the names and captures an era, this lean and mean tie-in serves up the greatest hits of cryptozoology circa 1975. 

Sun Classics, 1975

MAPS OF THE UNKNOWN: The Limbo of the Lost

From Limbo of the Lost, by John Wallace Spencer. Courtesy Bantam Books, 1974.

FLYING SAUCER OCCUPANTS by Coral and Jim Lorenzen

While more conservative UFO groups like NICAP shied away from stories of direct contact with alien entities, the Lorenzens and APRO went all in on compiling witness reports of FLYING SAUCER OCCUPANTS, including the scandalous Villas-Boas incident. Chapter 10 features an early appearance by alien abduction psychologist Leo Sprinkle, whose hypnotic regression techniques would unleash a flood of "repressed" UFO memories in the 1980s built on ideas of alien/human hybridization à la the Villas-Boas text.

Signet Books, 1967

GOD DRIVES A FLYING SAUCER by R. L. Dione

Some real choice revelations here ... and one Hell of a title! Available to read and download at archive dot org.

Bantam Books, 1969

FLYING SAUCERS ARE HOSTILE by Brad Steiger and Joan Whritenour

"This book just might save your life!" Don't leave home without it! Available to read and download at archive dot org.

Award Books, 1967

FLYING SAUCERS - HERE AND NOW! by Frank Edwards

Edwards had a long career in the paranormal field, starting with general Forteana before moving on to the burgeoning UFO scene of the 50s. This was his last book, published the year he died.

Bantam Books, 1967

ENCOUNTER CASES FROM FLYING SAUCER REVIEW edited by Charles Bowen

Does what it says on the tin. My favorite case is of the South African couple in Rhodesia who astral project to prehistoric times in their Peugeot.

Signet Books, 1977

ALIENS FROM SPACE by Donald Keyhoe

Signet Books, 1973