For every citation in your "References" page you must have at least one in text citation referencing that work. Similarly, when you provide a reference within the text of your research papers, you must also provide a corresponding citation in your "References" list.
For example, in this sentence from a hypothetical research paper:
Researchers found that negative tweets had a significant impact on the decision whether or not to see a particular film(Hennig-Thurau, Wiertz, & Feldhaus, 2015).
The in-text citation "(Hennig-Thurau, Wiertz, & Feldhaus, 2015)" would point readers to the following reference in the research paper's list of works cited:
Hennig-Thurau, T., Wiertz, C., & Feldhaus, F. (2015). Does Twitter matter? The impact of microblogging word of mouth on consumers' adoption of new movies. Journal of The Academy Of Marketing Science, 43(3), 375-394. doi:10.1007/s11747-014-0388-3
When the AUTHOR is named in the text:
When the AUTHOR is named only in the parenthetical citation:
When the AUTHOR and year are the same for two different citations
In the references list add "a" to the year of the citation and "b" to the year of the second citation, then cite in text as
When at all possible cite a the original source. So if the author of an article or book cites a source, find that source and quote directly from it. Then you know that the quote or paraphrase was not taken out of context.
When you do not have access to the original source, you need to mention the original source in the text of your paper, then have a parenthetical citation for the source where you actually found the information.
According to a report done by Wits Journalism in 2013, journalist, Jacob Mashokoa, “said tweeting was not all that simple, especially initially. In the early days ‘it was hell’ trying to tweet while also writing news headlines for the radio bulletin and taking pictures at the same time”(as cited in Daniels, 2014, p. 307).
In the above example I could not find the original report done by Wits Journalism, so I just mentioned the report in the body of my paper and put a parenthetical citation to the article that quoted from the report.
The in text citation then corresponds with the citation I have in my "References" page:
Daniels, G. (2014). How far does Twitter deepen democracy through public engagement?: An analysis of journalists' use of Twitter in the Johannesburg newsroom. Journal of African Media Studies, 6(3), 299-311. doi:10.1386/jams.6.3.299_
For more on cititing secondary (original) sources see: Secondary Sources (aka How to Cite a Source You Found in Another Source)
For more information about citing multiple authors see:
Lee, C. (2011, November 3). The proper use of et al. in APA style. The APA Style Blog. Retrieved from http://blog.apastyle.org/apastyle/2011/11/the-proper-use-of-et-al-in-apa-style.html