edited by Ulrich Ammon, Norbert Dittmar, Klaus J. Mattheier
Walter de Gruyter, 1988
Buku Referensi
Fishman, Joshua A.
Newbury House Publishers, 1972
Buku Teks SO
Bram, Joseph
Random House, 1955
Buku Teks SO
Malmstrom, Jean
Hayden Book Company, 1965
Buku Teks SO
Downes, William
Cambridge University Press, 2003
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