The Structure of Models of Peano Arithmetic. : Oxford University Press, 2006-06-29. Oxford Scholarship Online. 2007-09-01. Date Accessed 19 Jun. 2013 <http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198568278.001.0001/acprof-9780198568278>.
(2006-06-29). The Structure of Models of Peano Arithmetic. : Oxford University Press. Retrieved 19 Jun. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198568278.001.0001/acprof-9780198568278.
The Structure of Models of Peano Arithmetic. : Oxford University Press, 2006-06-29. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198568278.001.0001/acprof-9780198568278.
Kossak R, Schmerl J. The Structure of Models of Peano Arithmetic. Oxford University Press; 2006. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198568278.001.0001/acprof-9780198568278. Accessed June 19, 2013.