 Combinatorial Problems I Like, by Josh Cooper
 Open Problems  Graph Theory and Combinatorics, by Douglas B. West
 Open problems in combinatorics (pdf file) , by Alexander Postnikov
 Positivity Problems and Conjectures in Algebraic Combinatorics, by Richard Stanley
 Ten Problems in Combinatorics, Lecture given by GianCarlo Rota at the Conference on Combinatorics and Physics (CAP'98), held at the Los Alamos National Laboratory, August 1012, 1998. To be announced.
 Open Problems from the SIAM Activity Group Newsletter in Discrete Mathematics
 Problems on the Enumeration of Matchings (ps file) , by James Propp
 Unsolved Combinatorial Problems, by Zsolt Tuza
 Open Problems on Perfect Graphs, by Vašek Chvátal
 Problems in Signed, Gain, and Biased Graphs, compiled by Thomas Zaslavsky
 Unsolved Problems in Graph Theory, compiled by Stephen C. Locke
 Open Problems of Paul Erdös, by Fan R. K. Chung
 A list of problems on permutation groups, by Peter J. Cameron
 A problem on transitive permutation groups, by Peter J. Cameron
 Some Problems in Matroid Theory, compiled by Thomas Zaslavsky
 Unsolved Mathematics Problems, compiled by Steven Finch.
