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.
MightyFind can offer an initial "one stop shop" to search many of our full text databases of newspapers and magazines.