Hubbard, L. Ron, 1911-1986, author
Bridge Publications, Inc., 2012
Buku Referensi
Sroufe, L. Alan, author
Cambridge University Press, 1996
Buku Teks
Maeroff, Gene I., author
Palgrave Macmillan, 2006
Buku Teks
Nagazumi, Akira, author
Institute Of Developing Economies, 1972
Buku Teks
Janet Moyles, Jan Georgeson, and Jane Payler, editor
McGraw-Hill, 2011
Buku Teks