- A New Proof of the Four Colour Theorem - By Ashay Dharwadker. Includes profile, research papers for other algorithms, lecture notes, and student database.
- A=B - Downloadable combinatorics text by Marko Petkovsek, Herbert Wilf and Doron Zeilberger. Published by A. K. Peters.
- Algebraic Combinatorics via Finite Group Actions - A hypertext by A. Betten, H. Fripertinger and A. Kerber.
- ArXiv Front: CO Combinatorics - Combinatorics section of the Front for the Mathematics ArXiv.
- Catalogue of Lattices - A catalogue of different types with applications to packing spheres by Neil Sloane and Gabriele Nebe.
- Combinatorial Data - Brendan McKay's collection of miscellaneous tables in graph6 or sparse6 format.
- Combinatorics - MathWorld article with basic definitions and links.
- Counting Young Tableaux - An article on counting Young tableaux of bounded height by François Bergeron and Francis Gascon.
- Encyclopedia of Combinatorial Structures - Searchable database of structures with specifications and counts.
- Enumeration of Polyhedra - Enumeration of polyhedra with up to 9 faces by Steven Dutch.
- Enumeration of the Binary Trees - A note on Catalan numbers by Ivan Galkin.
- Extremal Combinatorics - With Applications in Computer Science by Stasys Jukna.
- G-Systems - Theory of chord structures to create music through algorithms by Vladimir Ladma.
- Generating Functions - Introduction to generating functions with interactive java applets by Alexander Bogomolny.
- Lectures in Combinatorics - An introduction to partially ordered sets, Dilworth's theorem, lattices and combinatorial geometries.
- On-line Dictionary of Combinatorics - An expanding web text by Joe Fields.
- Polya's Enumeration Theorem - An article on generating functions and Polya's theory of counting by Karl Dahlke.
- Series Expansions - Iwan Jensen counts polyominoes (aka lattice animals), paths, and various related quantities.
- Squared Squares - Tilings of squares and rectangles, the classical problem and variations.
- The Combinatorial Object Server - Select a type together with specific parameter values and COS will return a list of all such combinatorial objects.
- The Combinatorics Net - Maintained by Bill Chen.
- The Cutting Sticks Problem - An unsolved combinatorial problem by Frans Faase.
- The Math Forum Math Library - Combinatorics - Comprehensive catalog of websites relating to Combinatorics.
- Topics in Mathematics - Combinatorics - In the Mathematics Archive at University of Tennessee, Knoxville.
- Combinatorial Game Theory (13)
- Design Theory (37)
- Graph Theory (93)