Wolfram, Stephen
Addison-Wesley, 1991
Buku Teks
Botha, Rudolf P
Cambridge University Press, 2016
Buku Teks
Eberhard, Wolfram
Franche Ag, 1948
Buku Teks
Eberhard, Wolfram
Routledge & Kegan Paul, 1952
Buku Teks
Alfonso, Anthony
Sophia University LL Center of Applied Linguistics, 1980
Buku Teks