. Retrieved 2007-06-18 .   ^ Hatkoff, Isabella; Hatkoff, Craig and Kahumbu, Paula (2006). Owen & Mzee; The True Story of a Remarkable Friendship . New York : Scholastic Press . ISBN   0-439-82973-9 .   ^ "I Want A Hippopotamus For Christmas Lyrics" . Christmas-lyrics.org . http://www.christmas-lyrics.org/i-want-a-hippopotamus-for-christmas-lyrics.html . Retrieved 2007-12-20 .