The Case of the Vanishing Girls
Where the heck did they go? And why?
The first book is Bantam 1486, printed in 1956. The second is Bantam A2349, printed in 1962.
In the next set, we see Bantam A2330, printed in 1962 and Bantam J2961, printed in 1965.
All scans were contributed by Tom Daniels, of Springfield, MO.