I use Encyclopedia of Paden City Glass: Identification and Values reference book by Carrie and Jerry Domitz to identify Paden City Glass. They made so many etchings, and so many are obscure and not covered in general pattern books, that you need a company-specific reference if you like to go antiquing. Or flea marketing. Or thrifting. Or you have a box of glass without a name in the back corner. (Yes, I am describing myself!!)
A couple weeks ago I shared a book by a different author, also on Paden City, that is simply mediocre. If you are looking for a good reference this is the one to buy. Plus there is lots of eye candy here!