Open Universiteit and University of Greenwich
Butterworth-Heinemann, 1993
Buku Teks
Yeates, N. T. M.
Pergamon Press, 1975
Buku Teks
Ryan Dwi Saputra
2016
UI - Skripsi (Membership)
Scott, John Paul
The University of Chicago Press, 1958
Buku Teks
Macfadyen, A.
Pitman Publishing Corporation, 1963
Buku Teks