I just started a semester in Combinatorics and am looking for recommendations for books that clearly present the concepts. The textbook I am using is “Combinatorics: A Guided Tour” by David Mazur, which is great, but I would like more problems to work on. This is a slippery subject for me (I’ve been exposed to counting before in other math classes), and I feel that the more problems I work, the better my chances of understanding it are.