If I paraphrase a source that mentions other sources, which one do I cite?
You should consult an original source whenever possible. If, however, you paraphrase a source you did not personally consult, indicate this for your reader.
Let’s say you read the following passage from an article by Eric Pfanner in The New York Times, where the author draws on information from other sources:
Simon Jackman, a Stanford University professor whose work is published by The Huffington Post, and Drew Linzer, a professor at Emory University who runs a Web site called Votamatic.com, predicted the exact number of electoral college votes that Mr. Obama received—332. . . .
The following examples paraphrase information presented by Pfanner and cite his article as the source of the information, giving more or less detail and variously citing him in prose or parenthetically:
That Barack Obama would receive 332 electoral college votes in the 2012 election was accurately predicted by two pollsters (Pfanner).
In an article on political analysts published shortly after the 2012 presidential election, Eric Pfanner mentions two pollsters, Simon Jackman and Drew Linzer, who accurately predicted that Barack Obama would win 332 electoral college votes.
Two pollsters, Simon Jackman and Drew Linzer, accurately predicted that Barack Obama would receive exactly 332 electoral college votes in the 2012 election (Pfanner).
Paraphrasing an Indirect Quotation
You can even paraphrase a quotation from a source. Consider the following passage, from the same article:
“On the whole, the polls had it—were quite good,” Mr. Silver said in a video posted on The New York Times Web site.
If you want to summarize what Silver says rather than quote him directly, you could write the following:
Experts note that the polling in the 2012 election was generally accurate (Pfanner).
When quoting from an indirect source, see the eighth edition of the MLA Handbook, section 3.4.
Pfanner, Eric. “The Rise of the Quants in Political Prognostication.” The New York Times, 8 Nov. 2012, rendezvous.blogs.nytimes.com/2012/11/08/the-rise-of-the-quants-in-political-prognostication/.