--- YMSG8 ---
http://web.archive.org/web/20010801212305/http://www.venkydude.com:80/articles/yahoo.htm (Archive of http://www.venkydude.com/articles/yahoo.htm from 2001)

--- YMSG9/10 ---
http://libyahoo2.sourceforge.net/ymsg-9.txt (YMSG9)
http://www.engr.mun.ca/~sircar/ymsg9.htm (YMSG9)
http://web.archive.org/web/20020806213426/http://www.venkydude.com:80/articles/yahoo.htm (YMSG9, Archive of http://www.venkydude.com/articles/yahoo.htm from 2002)
http://web.archive.org/web/20021203013158/http://www.cse.iitb.ac.in/varunk/YahooProtocol.php (YMSG9)
http://web.archive.org/web/20030811172816/http://venkydude.com:80/articles/yahoo.htm (YMSG10, Archive of http://www.venkydude.com/articles/yahoo.htm from 2003)

--- YMSG11 ---
http://web.archive.org/web/20031205031525/venkydude.com/articles/yahoo.htm (Archive of http://www.venkydude.com/articles/yahoo.htm from 2003, first revision)
https://web.archive.org/web/20100615081758/http://www.venkydude.com/articles/yahoo.htm (Last archive of http://www.venkydude.com/articles/yahoo.htm from 2010, second revision)

--- YMSG12 ---
http://web.archive.org/web/20070910203807/http://www.ycoderscookbook.com/index.html

--- YMSG16 ---
https://kb.imfreedom.org/protocols/yahoo/
http://web.archive.org/web/20090623064155/carbonize.co.uk/ymsg16.html (Site no longer exists)
http://web.archive.org/web/20090912133315/http://www.adrensoftware.com/tools/yahoo_v16_protocol.php

--- YMSG18 ---
http://web.archive.org/web/20120626082942/http://www.adrensoftware.com/tools/yahoo_v16_protocol.php

--- Misc. ---
https://github.com/ifwe/digsby/blob/master/digsby/src/yahoo/
https://bitbucket.org/pidgin/main/src/soc.2006.msnp13/src/protocols/yahoo/

--- Yahoo! Messenger client archives ---
http://www.oldversion.com/windows/yahoo-messenger/


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Return codes for YMSG service 0x7D1 (Protocol-level Failure; taken from Yahsmosis `YMSGLib.INI`):

1004=Protocol Mismatch
1005=Unknown Data/Invalid Field number
1006=Incompatible software (or Cloaking)
; ^ happens when sending the old packets (eg: when using cloak)
1007=Invalid Protocol Version or Authorization
1011=Cookies Expired or Invalid
1013=Username format not acceptable.
: ^ ?
1014=Session expired or terminated
; ^ occurs after 52
1015=Session expired or invalid
;^ occurs after 1011 or 42 or 1051
1017=Authorized failed, a session was already active
1020=Invalid VendorID?
1051=Cookies Expired?