Peter Salim, author
Modern English Press, 1993
Buku Referensi
Ryder, Robert G.
Sage publications , 1987
Buku Teks
Ojeda, Oscar Riera, author
Rockport Publishers, 1996
Buku Teks
Bossuyt, Marc, author
Intersentia, 2016
eBooks
Sampson, Robert C., author
McGraw-Hill, 1965
Buku Teks