Singer, Ferdinand L., author
Harper & Row, 1980
Buku Teks
Stepin, P., author
Peace, [1964?]
Buku Teks
Ryder, G.H., author
Macmillan, 1983
Buku Teks
Willems, Nicholas, author
McGraw-Hill, 1981
Buku Teks
Stepin, P., author
Peace Publishers, 1964
Buku Teks