GMRP and GARP are described in:
IEEE 802.1D. "Local and Metropolitan Area Networks—Common Specifications—Media Access Control (MAC) Bridges." 1998. Chapter 10–13.
The router-to-router messages that track the locations of multicast recipients are described in the IETF Request for Comments (RFC) documents that follow:
RFC 1075—Waitzman, D., C. Partridge, and S.E. Deering. "Distance Vector Multicast Routing Protocol." RFC 1075, 1988.
RFC 1585—Moy, J. "MOSPF: Analysis and Experience." RFC 1585, 1994.
RFC 2117—Estrin, D., D. Farinacci, A. Helmy, D. Thaler, S. Deering, M. Handley, V. Jacobson, C. Liu, P. Sharma, and L. Wei. "Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification." RFC 2117, 1997.
RFC 2337—Farinacci, D., ...