Keep in mind this handy rule of thumb:
"When in doubt, CITE IT!"
It is never wrong to cite something. If you ever find yourself in a situation where you are not sure if you need to cite particular information (is it common knowledge or not?), citie it. That is the safest thing to do.
Click the link below to see a document describing how to cite articles from Literature Resource Center and LION in MLA format (7th edition).
Click the link below to see how to cite a book from ebrary (or another ebook vendor) in MLA format (7th edition).
Below is the link to the Duquesne Writing Center guide on developing paragraphs.