In text references can be:
Smith (2001) stated that "celll phone technonolgy has been a boon in countries such as India where traditionally getting a landline has been a lengthy and beaucratic process."
In his book on the development of cell phones, Smith (2001) explains in details the importance of this technology for countries such as India and China and how companies should be exploring ways to expand their markets there.
If the name of the author is part of the text, cite only the year of the publication in the text:
Example: Gossage (2011) recently conducted a ground-breaking study on the learnng styles of freshmen engineering students.
Otherwise place both the name and the year separated by a comma in parentheses at the end of the sentence:
Example: There are only a few in-depth studies of freshmen engineering students (Gossage, 2011).
If both the author and the year are part of the narrative, there is no need for parenthetical information (this is less common).
Example: In 2011, Gossage's study of freshmen engineering students showed that they were...
When a work has two authors, cite both names every time in the text.
When a work has three, four or five authors cite all authors the first time it appears in the text, but in subsequent ciations state the surname of the first author and add et al.
For more details check the APA manual: