Urantia Fondation, 1999
Buku Referensi
Rivers, Charlotte, author
Rotovision , 2009
Buku Referensi
Larsen, Michael
Writer?s Digest Books, 1985
Buku Teks
Chicago Urantia Foundation 1995,
Buku Teks
Knuth, Donald Ervin, 1938-, author
Addison-Wesley, 1986
Buku Teks