Fiengo, Robert. "Introduction: Ignorance and Incompleteness." Asking Questions: Using meaningful structures to imply ignorance. : Oxford University Press, 2007-05-03. Oxford Scholarship Online. 2011-10-03. Date Accessed 20 May. 2013 <http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199208418.001.0001/acprof-9780199208418-chapter-1>.
Fiengo, R.(2007-05-03). Introduction: Ignorance and Incompleteness. In Asking Questions: Using meaningful structures to imply ignorance. : Oxford University Press. Retrieved 20 May. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199208418.001.0001/acprof-9780199208418-chapter-1.
Fiengo, Robert. "Introduction: Ignorance and Incompleteness." In Asking Questions: Using meaningful structures to imply ignorance. : Oxford University Press, 2007-05-03. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199208418.001.0001/acprof-9780199208418-chapter-1.
Fiengo R. Introduction: Ignorance and Incompleteness. In: Fiengo R. Asking Questions: Using meaningful structures to imply ignorance. Oxford University Press; 2007. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199208418.001.0001/acprof-9780199208418-chapter-1. Accessed May 20, 2013.