Private Telecommunication Network (PTN) - Specification, functional model and information flows - Do not disturb and do not disturb override supplementary services; English version ETS 300363:1994
Private Integrated Services Network (PISN) - Specification, functional models and information flows - Do not disturb and do not disturb override supplementary services [ISO/IEC 14842 (1996), modified] (Endorsement of the English version EN 300363 V 1.2.1 (1999-03) as German standard)— 1 стр.
