How to Solve It: A New Aspect of Mathematical Method (Princeton Science Libr…
Condition Notes: Book is in very good condition and may include minimal underlining highlighting.
Mathematical Discovery on Understanding, Learning … Vol I and II by Pólya
Mathematical Discovery on Understanding, Learning, and Teaching Problem Solving, Volume II by George Pólya Volume one does not have a dust cover. Name inside front cover on volume one, otherwise no marks or highlighting. 
Mathematics and Plausible Reasoning, Volume 1: Induction and Analogy in…
Mathematics and Plausible Reasoning, Volume 1: Induction and Analogy in Mathematics by Polya, George May have limited writing in cover pages. Pages are unmarked. ~ ThriftBooks: Read More, Spend Less
How to Solve It: A New Aspect of Mathematical Method – Conway, John H.|Polya…
Condition Notes: The item is very worn but is perfectly usable. Signs of wear can include aesthetic issues such as scratches, dents, worn and creased covers, folded page corners and minor liquid stains.