Buck, Ross. "The Gratitude of Exchange and the Gratitude of Caring: A Developmental-Interactionist Perspective of Moral Emotion." The Psychology of Gratitude. : Oxford University Press, 2004-02-26. Oxford Scholarship Online. 2012-03-22. Date Accessed 19 Jun. 2013 <http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195150100.001.0001/acprof-9780195150100-chapter-6>.
Buck, R.(2004-02-26). The Gratitude of Exchange and the Gratitude of Caring: A Developmental-Interactionist Perspective of Moral Emotion. In The Psychology of Gratitude. : Oxford University Press. Retrieved 19 Jun. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195150100.001.0001/acprof-9780195150100-chapter-6.
Buck, Ross. "The Gratitude of Exchange and the Gratitude of Caring: A Developmental-Interactionist Perspective of Moral Emotion." In The Psychology of Gratitude. : Oxford University Press, 2004-02-26. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195150100.001.0001/acprof-9780195150100-chapter-6.
Buck R. The Gratitude of Exchange and the Gratitude of Caring: A Developmental-Interactionist Perspective of Moral Emotion. In: Emmons RA, McCullough ME. The Psychology of Gratitude. Oxford University Press; 2004. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195150100.001.0001/acprof-9780195150100-chapter-6. Accessed June 19, 2013.