1. ISO/TC184/SC4, Industrial automation systems and integration—product data representation and exchange—Part 11: Descriptive Methods: The EXPRESS Language Reference Manual (1992).
2. ISO/TC184/SC4, Industrial automation systems and integration—product data representation and exchange—Part 21: Clear Text Encoding of the Exchange structure (1994).
3. ISO/TC184/SC4/WG11 N088, EXPRESS-X Language Reference Manual (1999).
4. ISO/TC184/SC4, Industrial automation systems and integration—product data representation and exchange—Part 202: Application protocol: Associative Draughting (1996).
5. STEP-CDS Homepage, http://www.step-cds.de (2002).