Cross-referenced research literature and technical manuals completely matching the keyword registry records for Problem Solving.
Go!Games Trickledowns & StickLinks
Logic Safari, Book 2
The Riddle of Scheherazade: And Other Amazing Puzzles
Creative Understanding
On the Shoulders of Giants: New Approaches to Numeracy
The Penguin Book of Curious and Interesting Mathematics
CodeBreakers
Inferencing, Grades 3 - 4 (Basic Skills)
Moral Questions in the Classroom: How to Get Kids to Think Deeply About Real Life and Their Schoolwork