1. Information
1.1. Tutorial for Counter-Strike 1.5
CounterStrike/Tutorial (german)
2. Links / WebPages
2.1. Counter-Strike 1.5 Portal Webpage
http://www.cstrike15.bplaced.net
Containing a wiki with many pages around CS 1.5, serverlists, communities, players, help pages and downloads!
2.2. Information
http://www.open-game-protocol.org/