There are few exceptions to the Author-Page Number format for in-text citations that are worthy of note:
Authors With the Same Name
If your paper uses sources that include more than one author with the same last name, you must add the first initial to your in-text citations, or, if the initial is shared too, you must add the full first name.
When to Omit the Page Number
You may omit the page number in an in-text citation when you are citing the complete work, or if you are citing a quote from a one-page work.
If you are citing a work that does not have page numbers (e.g. films, television broadcasts, electronic sources with no pagination), include paragraph numbers if applicable, or any other location information that will help your reader find the source again (e.g. section number, chapter number, episode number, time or range of times for the clip you're referencing).
Common Works
When citing a common work of literature – one that is commonly studied and is available in various editions and versions – it is helpful to give information other than, or in addition to, the page number. This additional information, such as a book, chapter, verse, part, etc. will help your readers find your source in any edition of the work they happen to have. Examples of common works include Homer’s Iliad, any of Shakespeare’s plays, the Bible, etc.
