Some French manuscripts and published books from the eighteenth century are now available digitally. While some can be accessed with a simple internet search, it is a good idea to also search the following databases and catalogs (particularly if you are looking for manuscript material).
AND link words by AND to search for all words in the same resource
OR link words by OR to search for one word or another (instead of both/all words)
NOT to eliminate results with a certain term
“Quotations” – add quotations to a group of two or more words to search for the exact phrase