Hardcover
(Random House Books for Young Readers, Sept. 12, 1968)
HC, 1968, ex library, cover shows wear and rubbing along edges, corners, and spine, tape reinforces the hinges inside both front and back cover, smudges on fore edge, clean inside, tight binding.
Mass Market Paperback
(Scholastic Inc., Jan. 1, 1970)
Henry Allen's dog is missing - and he thinks it's been eaten by a dragon! On the night the dog disappeared, Mr. Allen swears he saw a huge dragon slither into the sea caves beneath his cliff-top house.Could Mr. Allen really have seen a dragon? The Three Investigators doubt it, but they're determined to find the missing dog. That means exploring those dark, dangerous caves>>>And whether or not Mr. Allen's dragon is real, something terrifying and deadly is lurking there!
Paperback
(Random House Books for Young Readers, May 12, 1978)
While vacationing on a California ranch, three boys decide to investigate strange wails that come from a mysterious cave where a famous outlaw disappeared.
Hardcover
(Random House Books for Young Readers, Aug. 12, 1971)
Hired to discover why a wild-animal farm's tame lion has become unpredictably nervous, three young detectives begin an investigation that uncovers a smuggling operation.