Although page number(s) are not required, for direct quotes, include the page number(s). See assorted examples below:
Basic format:
(Author's last name Year: Page number(s))
Examples:
One or two authors :
(Doe 2006: 29)
Multiple (3 or more) authors
First time listed:
(Doe, Richards, Jones, and Jones 2008: 212)
Subsequent cites:
(Doe et. al. 2007: 223)
No authors:
(First few words of reference list entry which is usually the Title Year Page number(s))
Example:
(Electronic reference formats 2007: 3)