Bass, Robert H.
Djambatan, 1960
Buku Teks
Hubbard, Leonard E., author
MacMillan, 1939
Buku Teks
Westview Press, 1980
Buku Teks
Sanchez-Sibony, Oscar, author
Cambridge University Press, 2014
Buku Teks
Aartsen, J. P. van, author
Pembangunan, 1953
Buku Teks