Jiggins, Chris D.
Oxford University Press, 2017
eBooks
edited by John L. Gittleman
Comstock , 1989
Buku Teks
Richardson, W. Norman
Macmillan, 1976
Buku Teks
edited by Peter Moore, R.J. Berry and A. Hallam
Grolier International, 1993
Buku Referensi
Haugen, Einar
Stanford University Press, 1972
Buku Teks