The British Academy
Oxford University Press, 1987
Buku Referensi
Murray, Peter
Prestel-Verlag, 1994
Buku Teks SO
Lunden, Staffan
Goteborg Universitet, 2016
Buku Teks SO
Sell's Publications, 1990
Buku Referensi
Cook, Chris
Macmillan, 1975
Buku Referensi