The Addition of Explicit Congestion Notification (ECN) to IP. K. Ramakrishnan, S. Floyd, D. Black. September 2001. http://www.faqs.org/rfcs/rfc3168.html
Management Guidelines & Operational Requirements for the Address and Routing Parameter Area Domain ("arpa"). G. Huston, Ed. September 2001. http://www.faqs.org/rfcs/rfc3172.html