A lot of 3 Cam Jansen mystery novels by David A. Adler, published by Scholastic Inc.
Includes: "The Mystery of the U.F.O." (1990), "The Ghostly Mystery" (1999), and "The Birthday Mystery" (2002).
Paperback editions, pre-owned with wear on the covers consistent with age.
The 2002 book has a sticky residue on the back cover and a personalization on the first page.