Proposed Official Standard for the Format of ARPA Network Messages. D. Crocker, K.T. Pogran, J. Vittal, et al. May 1977. http://www.faqs.org/rfcs/rfc724.html
Suggested Solution to the Naming, Addressing, and Delivery Problem for ARPANET Message Systems. D.P. Deutsch. September 1979. http://www.faqs.org/rfcs/rfc757.html