The simplest way to try to locate primary writings by an author is to do an Author search in HopeCat (remember, last name first!), and browse the list for collections and anthologies that are focused in this area. Keep an eye out for words in the title like:
Letters, correspondence, journal, diary, interviews, "on writing", "collected writings" (check record to see if this means fiction or non-fiction), papers.
When looking at the subject headings for a book you are unsure about, you may see some of the above terms. "Sources" is another words that usually signals that the text contains primary writings.
Historic newspapers are a great place to find reviews of a work of literature when it was originally published or contemporary discussions of the themes engaged by your work. The library has digital copies of three major historic newspapers:
If your work was published after 1850 you may find reference to it (or at least its themes) in the New York Times or Chicago Tribune. If your work is earlier than this and had international reach, it may be discussed in the Times of London.