4 links
ArchiRADAR
archiradar.com
Resource site for ArchiCAD users, with GDL objects, and a mailing list [more information in italian language].
GDL Alliance
gdlalliance.com
An independent, international professional association consisting of GDL authors, software developers, and building product manufacturers.
Graphisoft R&D Software Development Rt.
graphisoft.com
The developers of the architectural CAD software ArchiCAD and the facility management system ArchiFM.