And this one is far more rampant, as it involves academic textbooks for elementary and high schools that are updated every few years. The books bear the names of the original authors, but as time goes on - and authors retire, die, or whatever - uncredited writers take over the bulk of the work. And often use the same sources.

The NYT's Diana Jean Schemo compares passages between the 2005 edition of A HISTORY OF THE UNITED STATES, a high school history textbook by the Pulitzer Prize-winning historian Daniel J. Boorstin and Brooks Mather Kelley and the 2005 edition of another textbook, AMERICA: PATHWAYS TO THE PRESENT by different authors. And guess what? There are a ton of identical passages (though the publisher of the latter only claims "eight or nine" similarities between 2 1,000 page textbooks. Oh, yippee.)

Naturally, the authors were mortified. "They were not my words," said Allan Winkler, a historian at Miami University of Ohio, who wrote the PATHWAYS book with Andrew Cayton, Elisabeth I. Perry and Linda Reed. "It’s embarrassing. It's inexcusable." But the incident highlights the use of uncredited writers and how it's easy to let stuff slip in over time. "The publishers have a brand name and that name sells textbooks," said Gilbert T. Sewall, director of the American Textbook Council. "That's why you have well-established authorities who put their names on the spine, but really have nothing to do with the actual writing process, which is all done in-house or by hired writers."