Salomaa, Arto
Jewels of formal language theory / Arto Salomaa
Computer Science Press, 1981
 Buku Teks
Koenen, Liesbeth
Vermogen te verlangen (9 (negen) letters)*
Nijgh & Van Ditmar, 1991
 Buku Teks
Vendryes, J. (Joseph), 1875-1960, author
Language : a linguistic introduction to history
Routledge, 1996
 Buku Teks
Whatmough, Joshua
Language: a modern synthesis / Joshua Whatmough
The New American Library, 1956
 Buku Teks
Diamond, A. S. (Arthur Sigismund)
The History and origin of language / A.S. Diamond
Methuen , 1959
 Buku Teks