Cannadine, David
Papermac, 1996
Buku Teks SO
edited by Hilary Lewis Ruttley
[Publisher not identified], 1995
Buku Teks
Rogers, Margaret
Oceana Publications, 1969
Buku Teks
Willcox, William B.
D.C. Health, 1988
Buku Teks SO
Willcox, William B.
D.C. Heath, 1988
Buku Referensi