Hewlett, Richard G.
Pennsylvania State University Press, 1962
Buku Referensi
Bernath, Peter F.
Oxford University Press, 1995
Buku Teks SO
Dean, Gordon
Alfred A. Knopf, 1957
Buku Teks
Fraga, Serafin
North-Holland, 1981
Buku Teks
Moeso Suryowinoto
Kanisius, 1990
Buku Teks