Fisher, Ronald A., author
Oliver and Boyd , 1950
Buku Teks
Johnson, Palmer O., author
Prentice-Hall, 1953
Buku Teks
Johnson, Palmer O., author
Rand McNally, 1959
Buku Teks
Kendall, M.G., author
Griffin , 1968
Buku Teks
Tippett, L. H. C.
Williams and Norgate , 1952
Buku Teks