What you can copyright and therefore protect from infringement is:1) your specific layout and design;2) your specific edits or annotations, (or, for foreign quotes), translations) of the quotes.What you can't copyright are the quotes themselves. So, to take an example inspired by the upcoming "Abraham Lincoln: Vampire Hunter" film: you could not copyright the Gettysburg address or prevent someone else from publishing it. But if your version starts "Four score and seven years ago [since a score is twenty years, this is a poetic way of saying 87 years ago]" and is laid out in a particular, unique fashion, no one could copy the exact edited or annotated , uniquely laid out, version you published. They could go to the original, which is public domain, and come up with their own published version.So from what you write, there may be infringement and you may have a claim, if they are copying your site directly. You should speak in greater detail with an intellectual property attorney.