Hankes, Elmer Joseph
A universal second language
Hankes Foundation, 1992
 Buku Teks SO
A Universal second language
The Hankes Foundation, 1992
 Multimedia
The universal dictionary of the English language
edited by Henry Cecil
George Routledge & Sons, 1946
 Buku Referensi
Lyons, John
Natural language and universal grammar
Cambridge University Press, 1991
 eBooks
Lyons, John
Natural language and universal grammar : essays in linguistic theory; Volume 1
Cambridge University Press, 1991
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