MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies. N. Borenstein, N. Freed. September 1993. http://www.faqs.org/rfcs/rfc1521.html
Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy. V. Fuller, T. Li, J. Yu, K. Varadhan. September 1993. http://www.faqs.org/rfcs/rfc1519.html
MIME (Multipurpose Internet Mail Extensions) Part Two: Message Header Extensions for Non-ASCII Text. K. Moore. September 1993. http://www.faqs.org/rfcs/rfc1522.html