1996GSM 08.52-1996 Digital Cellular Telecommunications System; Base Station Controller - Base Transceiver Station (BSC - BTS) Interface; Interface Principles (GSM 08.52; Version 5.0.0)
1993GSM 08.52-1993 European Digital Cellular Telecommunication System (Phase 2); Base Station Controller (BSC) to Base Transceiver Station (BTS) Interface Principles