Hubbard, L. Ron, 1911-1986, author
Bridge Publications, Inc., 2012
Buku Referensi
Ehrlich, Paul R., author
McGraw-Hill, 1976
Buku Teks
Elsevier Science Inc., 660, 2018
Majalah, Jurnal, Buletin
Galbraith, John Kenneth, 1908-2006, author
Houghton Miffiln, 1958
Buku Teks
Davis, Kingsley, 1908-1997, author
Macmillan, 1949
Buku Teks