If it's an op-ed—that is, an opinion article published by someone who isn't the publication's editor—you might insert "Op-ed" at the end of the entry: David Gergen "A Values Question." US News & World Report, 11 February 2001, p. 28. Cited by author and date. If the op-ed was written by the publication's editor or another prominent person, you can also include the name of the writer after the term "op-ed": Richard Cohen "The Future Is Female." The Washington Post, 7 April 2013. Otherwise, follow the usual rules for citing sources in academic work. In short, put the name of the writer-editor or commentator-author before the publication title and place of publication. Then provide the page number on which the article appears.