In what sense is Biggs a "foundational" author? I looked up his book titled *Discrete Mathematics*, which I'd never heard of before, and the first edition came out in 1985. I assure you that the field of discrete math was well established before the 1980s.

A nice book to look at is *Concrete Mathematics* by Graham, Knuth, and Patashnik. It even has its own Wikipedia page, at which the bottom lists the chapter topics.