A writer who is using MLA style wants to refer his readers to some additional sources that he doesn't directly reference within his paper. Which of the following are ways he could do this?

By adding an index section at the back of the book or paper where he could put his sources and all additional resources.

why biographies are better than plays

explanation someone is saying they like biographies better

the dictionary definition of ubiquitous is "present, appearing, or found everywhere".