Geoff Green, Ken Petford, Alan Short, David Walker
John Muray, 1975
Buku Referensi
Derry, Gregory N.
Princeton University Press , 1999
Buku Teks SO
John Murray , 1976
Buku Teks SO
Menard, Henry W.
Massachusetts Harvard University Press , 1971
Buku Teks SO
Victor Gollancz , 1956
Buku Teks