Rubenstein, William
West A Tomson Reuters Busines, 2011
Buku Teks SO
general editor, Irving J. Sloan
Oceana Publications, 1987
Buku Teks
White, B.R.
Oceana Publications, 1986
Buku Teks
Davies, Jack
West Publishing, 1975
Buku Teks
Wood, William
Percival Marshall, 1949
Buku Teks