https://www.google.com/patents/US6269361
and then there are the patents filed by Friendster, that Facebook later acquired:
https://www.theguardian.com/technology/pda/2010/aug/05/faceb...
https://www.google.com/patents/US6269361
and then there are the patents filed by Friendster, that Facebook later acquired:
https://www.theguardian.com/technology/pda/2010/aug/05/faceb...