Crystal, David (2014): . Oxford University Press. ISBN 0-19-968047-7. Donaldson, Gary A. (2009): . Rowman & Littlefield. ISBN 0-7425-4820-1. Joyner, David Lee (2008): , 3. utg., McGraw-Hill Education. ISBN 0-07-352657-6. McDonald, Chris (2009): . Indiana University Press. ISBN 978-0-253-00404-8. Smith, Chris (2006): . Greenwood Press. ISBN 0-313-32937-0. Waksman, Steve (2009): . University of California Press. ISBN 0-520-25310-8.