For graduate-level introductory combinatorics, texts by Cameron and Van Lint-Wilson are recommended for their solid content. Additionally, Diestel's "Graph Theory" is suggested as a valuable resource. The discussion also highlights the importance of understanding mathematical physics techniques for solving two-dimensional lattice models, specifically mentioning the Yang-Baxter equation and Fermionic methods involving the Pfaffian. A resource for further reading is the book "Exactly Solved Models in Statistical Mechanics" by Baxter, which is available for free download, although it is noted that Baxter does not refer to the Yang-Baxter equation by that name in his work.
