RFC 2186:Internet Cache Protocol (ICP), version 2
RFC-Ref

5. References

[1] Fielding, R., et. al, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2068(-> 2616draft), UC Irvine, January 1997.
[2] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform Resource Locators (URL)", RFC 1738(-> 4266prop | 4248prop), CERN, Xerox PARC, University of Minnesota, December 1994.
[3] Bowman M., Danzig P., Hardy D., Manber U., Schwartz M., and Wessels D., "The Harvest Information Discovery and Access System", Internet Research Task Force - Resource Discovery, http://harvest.transarc.com/.
[4] Wessels D., Claffy K., "ICP and the Squid Web Cache", National Laboratory for Applied Network Research, http://www.nlanr.net/~wessels/Papers/icp-squid.ps.gz
[5] Wessels D., "The Squid Internet Object Cache", National Laboratory for Applied Network Research, http://squid.nlanr.net/Squid/

Google
Web
RFC-Ref