1. Language Implementation Validation. Proceedings of the Two-Day Workshop held by BNI, GMD and NCC at The National Computing Centre, Manchester, England, prepared by; N. Malagardis, F. v. Sydow and T. Wells. The National Computing Centre, Manchester, April 1980.
2. Conformance Testing Services (CTS), Fact Sheets, 1988. (These include sheets on CTS for telecommunication.) To be obtained from the Commission of the European Communities, Directorate General XIII, 200 rue de la Loi, B-1049 Brussels.
3. Berthold Kirsch: Conformance testing for the Graphical Kernel System (GKS). In: Forward with Harmonized Conformance Testing Services, Proceedings of the CTS Technical Days, Brussels, October 1–2, 1987, pp. 85–94. IOS, Van Diemenstraat 94, 1013 CN Amsterdam, The Netherlands, and IOS, P.O. Box 2848, Springfield, VA 22152–2848, USA. viii + 178 pages (1988). ISBN 90–5199-001–6.
4. Conformance and certification of graphics systems. In: Computers and Graphics, Vol. 8, 1(1984) pp. 1–112: special issue, guest editor Günther E. Pfaff. Pergamon Press, New York and Oxford; ISBN 0–08-031422–8, ISSN 0097–8493.
5. Güte- und Prüfbestimmungen Software, RAL-GZ 901, korrigierte 2. Auflage, November 1985 (in German only). To be obtained from Gütegemeinschaft Software e.V. (GGS), Postfach 71 08 64 (VDMA), D-6000 Frankfurt am Main 71. (Revised version to appear.)