Book recommendation for Putnam/Olympiads

Question

I have been concentrating on olympiad questions, and PUTNAM exams, Putnam is my main focus. Can you suggest a book from one of these:

1. Problem Solving Strategies By Arthur Engel
2. Putnam and Beyond by Andreescu Titu et. al

First, can you tell me which one is better from the above? I only have one choice?

Any other book recommendations is greatly appreciated!

Answer 1

How could you do better than the problems and solutions themselves for past Putnam exams?

1. 1938-1964
2. 1965-1984
3. 1985-2000

For a Putnam archive of past exam questions and solutions, check out this website maintained by Kiran Kedlaya.

There are, of course, many other resources, but these are by far the best I know to date.