Gilluly, James, author
W.H. Freeman, 1959
Buku Teks
Billings, Marland P., author
Prentice-Hall, 1954
Buku Teks
Lange, Oktavii Konstantinovich, 1883-1975, author
Foreign Languages Publishing House , 196?
Buku Teks
Levorsen, A.I.
San Fransisco: W.H. Freeman, 1967
Buku Teks
Himus, Godfrey W., author
Harmondsworth, Middlesex, 1954
Buku Referensi