Strictly as a reference for serious students I should mention "Boobpedia" the "Encyclopedia of big boobs" covering thousands of celebrities, actresses, models and athletes. Lots of info includein size, appearances, real or enhanced etc.
Don't know the rules here about posting links here, Just type "Boobpedia" into your favorite search engine. Warning: Some of the girls pages post a topless image when available; of course I don't look at those ... too much.