Keller, Perry. "International Trade in Media Goods and Services." European and International Media Law: Liberal Democracy, Trade, and the New Media. : Oxford University Press, 2011-05-01. Oxford Scholarship Online. 2011-09-22. Date Accessed 22 May. 2013 <http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198268550.001.0001/acprof-9780198268550-chapter-6>.
Keller, P.(2011-05-01). International Trade in Media Goods and Services. In European and International Media Law: Liberal Democracy, Trade, and the New Media. : Oxford University Press. Retrieved 22 May. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198268550.001.0001/acprof-9780198268550-chapter-6.
Keller, Perry. "International Trade in Media Goods and Services." In European and International Media Law: Liberal Democracy, Trade, and the New Media. : Oxford University Press, 2011-05-01. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198268550.001.0001/acprof-9780198268550-chapter-6.
Keller P. International Trade in Media Goods and Services. In: Keller P. European and International Media Law: Liberal Democracy, Trade, and the New Media. Oxford University Press; 2011. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780198268550.001.0001/acprof-9780198268550-chapter-6. Accessed May 22, 2013.