Vintage Barbie

I need to know how to identify vintage Barbie dolls, a few dolls that I have watched two different dates of them at the back of the neck or the butt, which is the correct date? Is there anything else I need to look? any information would be greatly appreciated, Thanks.

There is a book that I had called the public library
"Collectors Encyclopedia of Barbie Doll" by J. Michael Augustyniak. It has lots of information on the identification of Barbies.
Most libraries carry books on Barbie. another online source that is good is: http://collectdolls.about.com/library/blmenu2.htm
Hope this helps.

chewed hair tied in plastic

Barbie is simple and difficult to identify .... go to the library and get a book just Barbies ... dates on the buttocks and then you have the hair color and lip color and swimwear to face .... Mattel may just want to get everything there replacement parts and begin to assemble ... and you're done with a bouillabaisse of a barbie ...... and then they had the barbie plastic bag ... and counting and ... you need a book ....

because the terminally sad and friendless pay huge amounts of money (often over their entire earnings for years at McDonalds) to buy. And hobby of someone who envolvement examining the butt of Barbie dolls in need of special assistance.

No old enough to be classified as vintage.