Terminal equipment and protocols for telematic services : recommendations T.65 - T.101, T.150 - 390 / International Telecommunication Union
Terminal equipment and protocols for telematic services : recommendations T.400 - T.418 / International Telecommunication Union
Data communication over the telephone network : series V recommendations / International Telecommunication Union
Data communication networks : services and facilities, interfaces: recommendations X.1 - X.32 / International Telecommunication Union