Refer to the following RFCs for more information about RIP. You can access all RFCs online at www.isi.edu/in-notes/rfc xxxx .txt, where xxxx is the number of the RFC that you want to read.
RFC 1058, "Routing Information Protocol"
RFC 1723, "RIP Version 2"
RFC 2453, "RIP Version 2"
RFC 1582, "Extensions to RIP to Support Demand Circuits"
RFC 2091, "Triggered Extensions to RIP to Support Demand Circuits"