Followig references are related to NGAP Test Specification TS 103 920-2
[1]	ETSI TS 138 413: "5G;NG-RAN; NG Application Protocol (NGAP) (3GPP TS 38.413 Release 16)".
[3]	ETSI TS 123 502: "5G; Procedures for the 5G System (5GS) (3GPP TS 23.502 Release 16)".

Followig references are related to 5G NAS Test Specification TS 103 921-2
[1]	ETSI TS 124 501: "5G; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 (3GPP TS 24.501  Release 16)".