ebay - Large Online Auction website. Simple registration required for bidding. Many categories in addition to books. (ebay search tips).
NVvA, Nederlandsche Vereeniging van Antiquaren, The Dutch Antiquarian Booksellers' Association, founded in 1935 with the object of promoting reliability
in the trade of old books and prints.
ANTIQBOOK antiquarian booksellers online ANTIQBOOK, provided by NAN (The Netherlands Antiquarian Booksellers Network).
Philadelphia Rare Books & Manuscripts Company: Early Printed Books, Substantive Manuscripts. U.S. & Latin America, Mexico & New World Languages, Hispanica, Histories & the History of Ideas, Travels, Law, Religion, & Bibles (all prior to 1820).
This will find and list all files containing the term(s) of your search. Then you can use your browser's "find" command to search just those pages.