APA-referens (7:e uppl.)
Humphreys, K. (2011). Holiday letters: A CEO shares his heart throughout the year. Lifestyle Impact Ministries.
Chicago-referens (17:e uppl.)
Humphreys, Kent. Holiday Letters: A CEO Shares His Heart Throughout the Year. Kent Humphreys: Lifestyle Impact Ministries, 2011.
MLA-referens (9:e uppl.)
Humphreys, Kent. Holiday Letters: A CEO Shares His Heart Throughout the Year. Lifestyle Impact Ministries, 2011.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.