2010ETSI TR 102 021-5-2010 Terrestrial Trunked Radio (TETRA); User Requirement Specification TETRA Release 2.1; Part 5: Interworking and Roaming (V1.2.1)
2002ETSI TR 102 021-5-2002 Terrestrial Trunked Radio (TETRA); User Requirement Spicification TETRA Release 2; Part 5: Interworking and Roaming V1.1.1