http://www.cern.ch 
http://lcweb.loc.gov/marc/ 
http://www.exlibris.co.il/ 
http://weblib.cern.ch/ 
http://www.ics.uci.edu/WebSoft/MOMspider/WWW94/paper.html 
http://www.w3.org/Addressing/ 
http://purl.oclc.org/OCLC/PURL/INET96 
http://www.doi.org/ 
http://www.periwinkle.net/plinker.html 
http://www.netimpact.net/content/link.html 
http://www.w3c.org/ 
http://www.crossref.org/