Graphical language features in ALGOL 68. - Ernst Denert; G. Ernst; Harald Wetzel (SIGGRAPH, 1974)

GRAPHEX68 Graphical language features in ALGOL 68. - Ernst Denert; G. Ernst; Harald Wetzel (Comput. Graph., 1975)

GKS im Anwendungsbereich CAD. - Reiner Anderl; Joachim Rix; Harald Wetzel (Inform. Spektrum, 1983)