Gottlieb, Bill
Rodale, 2000
Buku Teks SO
David W. Sifton
Ballantine Books, 2000
Buku Teks SO
C. Norman Shealy, Richard Thomas, Anne Townley, Viv Croot, Caro Ness
Element Books Limited, 1996
Buku Teks SO
Evans, Mark
Lorenz Books, 1999
Buku Teks SO
Mantle, Fiona
Elsevier , 2009
Buku Teks SO