For parenthetical author-date references, "parenthetical" means that the name of the author and the date of the work you are citing are placed in (parentheses). They are presented in the text of your paper like this:
Author’s name in text (no page number):
Walker (2000) compared reaction times. . .
Author’s name in reference (no page number):
In a recent study of reaction times (Walker 2000). . .
Author’s name in text (page number):
According to Cuno (2008, 3), “Most often it falls to the museum to prove that it has the right to keep the questioned unprovenanced antiquity."
Author’s name in reference (page number):
The argument runs that, “The term 'Czechoslovak' had become a rich source of contention almost immediately after the state's formation,” (Innes 2001, 16).
There is no comma between the author's name and the year of publication. If you are citing a direct quotation from a work, you need to include the page number(s) on which the quote appears in your reference following the year of publication -- this time with a comma.
If a book has four or more authors, list only the first author's name followed by the words "et al." and any page numbers if necessary. For example: (Hughes et al. 2008, 24-25).