Opening Official Maps in Hammer [Counter-Strike: Global Offensive] [Tutorials]
J.A.C.K. :: Official Website
Valve Hammer Editor - Valve Developer Community
Valve Hammer Editor - Combine OverWiki, the original Half-Life wiki and Portal wiki
Mapping with Hammer Tips – Lagspike
Valve Hammer Editor for Windows - Free Download
Found Logical on valve hammer editor ! - 3D - Mapcore
Josh Dowell on Twitter: "Just released some updated mapping tools for Source 2013. Focuses on improving stability and user-experience. Hammer is way, way more stable now, should only crash a fraction of