Answered By: Gabe Gossett Last Updated: Jan 14, 2016 Views: 7507
This depends on how you are citing them. If you are citing them in-text more than once, and you are referring to the same source each time, then you can simply reuse that same in-text reference with a single entry on your references page at the end.
If you are citing the same author, but from different sources, you may have to follow different rules. Let's say you are citing an author named Jane Doe three times. If each of her articles or books are published in different years, then you don't need to do anything different than you normally would. Let's say she published articles in 2009, 2011, and 2012. Then each entry would just be (Doe, 2009), (Doe, 2011), and (Doe, 2012).
If, on the other hand, all of her articles were published in the same year, then you would need to add letters to differentiate between them. Let's say they were all published in 2009. So then it would be (Doe, 2009a), (Doe, 2009b), and (Doe, 2009c). In your reference list you should then add the corresponding letters.
For more information see APA Manual page 178.