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