I just had a nice email from a new collector asking about reference books I recommend. These are the books I have and use regularly:
The two books that are the best source for general information are Colorful Tablecloths by Barineau and Henderson. The second, older book is Collector's Guide to Vintage Tablecloths by Glasell.
If you're interested in collecting souvenir tablecloths, there's Souvenir Linens by Glasell.
If you're interested in Wilendurs, then Elegant Table Linens from Wiel and Durrse by Hayes.
All of the ladies I've just mentioned were founding members (with me) of the Vintage Tablecloth Lover's Club. I'm not very active there any more (I don't have time) but it has a member board where you can post questions. There are also collector's groups popping up on Facebook.