Winokur, George, author
W.B. Saunders, 1986
Buku Teks
Olumoroti, Olumuyiwa John, author
Elsevier, 2005
Buku Teks
edited by Joseph D. Noshpitz
John Wiley & Sons, 1997
Buku Referensi
Curran, Desmond, author
Churchill, Livingtone, 1972
Buku Teks
Sadock, Benjamin J., 1933-, author
Wolters Kluwer, 2015
Buku Teks