[1] [CITE@en[RFC 5546 - iCalendar Transport-Independent Interoperability Protocol (iTIP)]]
( ([TIME[2011-05-08 15:25:12 +09:00]] 版))
<http://tools.ietf.org/html/rfc5546>

[2] [CITE@en[RFC 5546 - iCalendar Transport-Independent Interoperability Protocol (iTIP)]]
([TIME[2015-04-19 16:20:38 +09:00]] 版)
<https://tools.ietf.org/html/rfc5546>