IPv4
RFC 791 - Internet Protocol
RFC 950 - Internet Standard Subnetting Procedure
RFC 1112 - Host Extensions for IP Multicasting
RFC 1518 - An Architecture for IP Address Allocation with CIDR
RFC 1519 - Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy
RFC 1597 - Address Allocation for Private Internets
RFC 1817 - CIDR and Classful Routing
RFC 2101 - IPv4 Address Behaviour Today