1. Standardized languages for telecommunication systems;Adamis;Computer Standards & Interfaces,2005
2. ITU-T Recommendations Z series Languages and general software aspects for telecommunication systems, http://www.itu.int/rec/T-REC-Z/en
3. ITU-T – International Telecommunications Union Draft Recommendation Z.680 (02/03) ASN.1: Abstract Syntax Notations One, Geneva, Switzerland,2003
4. ITU-T – International Telecommunications Union Draft Recommendation Z.151 (02/03) GRL: Goal-oriented Requirement Language,2003
5. ITU-T – International Telecommunications Union Recommendation Z.150 (02/03) URN: User Requirements Notations – Language requirements and framework,2003