Gregory, Robert Henry
Chatto and Windus, 1963
Buku Teks
Orilia, Lawrence S.
McGraw-Hill, 1982
Buku Teks SO
Alagar, Vangalur S.
Prentice-Hall, 1989
Buku Teks SO
Clifton, H.D.
Auerbach, 1971
Buku Teks
Awad, Elias M.
Prentice-Hall International, 1980
Buku Teks