1. D. Amyot. Introduction to the User Requirements Notation: Learning by Example. To appear in: Communication Networks, 2003.
2. ITU-T. Recommendation Z.150, User Requirements Notation (URN) — Language Requirements and Framework. Geneva, Switzerland, 2003. http://www.UseCaseMaps.org/urn/
3. R. J. A. Buhr, (1998) Use Case Maps as Architectural Entities for Complex Systems. IEEE Transactions on Software Engineering. Vol. 24, No. 12, December 1998, 1131–1155.
4. ITU-T, URN Focus Group. Draft Rec. Z.152 — UCM: Use Case Map Notation (UCM). Geneva, Switzerland, 2002.
5. ITU-T. Recommendation Z.100, Specification and Description Language (SDL). Geneva, Switzerland, 2000.