Q. How do i cite a source within a source in APA style (Ex. Many Journal articles site other sources...how i cite one of their citations?)

You are in luck! the APA blog tells how to deal with it here: http://blog.apastyle.org/apastyle/2010/05/secondary-sources-aka-how-to-cite-a-source-you-found-in-another-source.html. Here is their advice:

In your reference list, provide a reference for the source you read. This is known as the secondary source because it is one step removed from the original source of the idea or quotation. In your text, name the original work and provide the citation for the secondary source.

Let’s look at an example:

In his e-mails, Smith argued that asynchronous line dancing would be the next Internet meme (as cited in Jones, 2010).

Jones (2010) would be the reference you include in your reference list. Also, note that by mentioning the original format of the information (in this case a series of e-mail messages), you not only specify that this is a secondary source but also give the reader an indication of why that’s the case. Although it’s not a requirement, mentioning the original format answers this potential question for the reader so he or she can focus on the content!