EXERCISE APA 4–5 APA documentation: reference list - 6 of 10: The student has summarized information from an article in volume 477 of the scholarly journal Nature, published on September 15, 2011. The article, titled “Natural Gas: Should Fracking Stop?,” was written by Robert W. Howarth, Anthony Ingraffea, and Terry Engelder and appeared on pages 271-275. The article has the DOI 10.1038/477271a.