Chess Problem Database Server (by Gerd Wilts)

Yet Another Chess Problem Database (by Dmitri Turevski)

WFCC - World Federation for Chess Compositions

FIDE - World Chess Federation

Russian Chess Federation

Russian-language FORUM about chess composition

British Chess Problem Society

Finnish Chess Problem Society

Dutch Chess Problem Society

Die Schwalbe

Mat Plus

StrateGems

e4 e5

The Ural's Problemist

Chess Fonts

Chess Programs and Utilities