You are required to use MLA format to cite all your sources. If you decide to use a website, you will need to create your citation yourself. Websites do not provide reliable citations. NoodleTools can help you with that.
You can only access links labeled "View full text from Hathi Trust." Helpful for: Isaac Wilkins, Mercy Otis Warren, Roger Sherman, and Soame Jenyns. (The book on Jenyns is written in Colonial-era spelling, when "f" was used as "s.")