Aigner, A Course in Enumeration (not on reserve)
Aigner, Combinatorial Theory (not on reserve)
Graham & Rothschild & Spencer, Ramsey Theory
Hall, Combinatorial Theory
Lindner & Rogers, Design Theory
Matousek, Using the Borsuk-Ulam Theorem
Pach-Agarwal, Combinatorial Geometry
Petkovsek & Wilf & Zeilberger, A=B (that's the title)
Stanley, Enumerative Combinatorics (Vol I&II)
van Lint & Wilson, A Course in Combinatorics