Gordon, Michael, author
Kogan Page, 1984
Buku Referensi
Gordon, Michael, author
Kogan Page, 1986
Buku Referensi
edited by Ernest A. Baker
Cassell, 1935
Buku Referensi
Victoria Neufeldt, Andrew N. Sparks, editor
Simon & Schuster, 1989
Buku Referensi
Aveyard, Victoria, author
Mizan Publika, 2017
Buku Teks