Davidson, Ivor J. "Book Three." Ambrose: De Officiis: Edited with an Introduction, Translation, and Commentary (Two Volume Set). : Oxford University Press, 2002-02-28. Oxford Scholarship Online. 2004-08-01. Date Accessed 18 Jun. 2013 <http://www.oxfordscholarship.com/view/10.1093/0199245789.001.0001/acprof-9780199245789-chapter-23>.
Davidson, I.(2002-02-28). Book Three. In Ambrose: De Officiis: Edited with an Introduction, Translation, and Commentary (Two Volume Set). : Oxford University Press. Retrieved 18 Jun. 2013, from http://www.oxfordscholarship.com/view/10.1093/0199245789.001.0001/acprof-9780199245789-chapter-23.
Davidson, Ivor J. "Book Three." In Ambrose: De Officiis: Edited with an Introduction, Translation, and Commentary (Two Volume Set). : Oxford University Press, 2002-02-28. http://www.oxfordscholarship.com/view/10.1093/0199245789.001.0001/acprof-9780199245789-chapter-23.
Davidson IJ. Book Three. In: Davidson IJ. Ambrose: De Officiis: Edited with an Introduction, Translation, and Commentary (Two Volume Set). Oxford University Press; 2002. http://www.oxfordscholarship.com/view/10.1093/0199245789.001.0001/acprof-9780199245789-chapter-23. Accessed June 18, 2013.