John Hartley [and others]
Rinehart and Winston, 1962
Buku Teks SO
edited by John Miksic
Archipelago Press, [date of publication not identified]
Buku Teks
Bone, Robert G.
Littlefield, Adam, 1957
Buku Teks
Charles E. Tutle Co.Inc, 1959,
Buku Referensi
Veit, Richard
Pearson, 2001
Buku Teks SO