1. CCITT Recommendation X.25, FASCICLE VIII.2, IXth Plenary Assembly 1988 (Blue Book) (Study Group VII).
2. CCITT Recommendation X.2, FASCICLE VIII.2, IXth Plenary Assembly 1988 (Blue Book) (Study Group VII).
3. Digital Subscriber signalling system No. 1 (DSS 1), Signalling specification for frame mode bearer service, CCITT Recommendation Q.933.
4. IEEE, IEEE Standard for Local and Metropolitan Area Networks: Overview and architecture, IEEE Standards 802-1990.
5. Core aspects of Q.922 for use with frame relaying bearer service, Annex A to CCITT Recommendation Q.922, Draft 1992 (Blue Book).