TCP and UDP with Bigger Addresses (TUBA), A Simple Proposal for Internet Addressing and Routing. R. Callon. June 1992. http://www.faqs.org/rfcs/rfc1347.html
A Two-Tier Address Structure for the Internet: A Solution to the Problem of Address Space Exhaustion. Z. Wang, J. Crowcroft. May 1992. http://www.faqs.org/rfcs/rfc1335.html