Post your link.

Rotated dies.
http://www.rotateddies.com/

Error coins.
http://www.byersnc.com/relatedlinks.html

http://koinpro.tripod.com/ErrorVarietyList.htm

Doubled die.
http://doubleddie.com/

Double die and die varieties.
http://coins.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=coins&cdn=hobbies&tm=24&f=00&tt=13&bt=0&bts=0&zu=http%3A//www.coppercoins.com/

Mule coin.
http://en.wikipedia.org/wiki/Mule_%28coin%29

http://errorcoin.blogspot.com/

http://www.bestcoin.com/US-Mint-Error-Coins.htm

For future reference most of the writers and major collector are either from USA and Europe most of there work are in specialized coin books and recognized in world standard catalog we will just start in here for specification and specialization for error,varieties and oddities for Philippine coin,just a comment.