The Hague, 1972
Buku Teks
edited by Ulrich Ammon, Norbert Dittmar, Klaus J. Mattheier
Walter de Gruyter, 1987
Buku Referensi
edited by Ulrich Ammon, Norbert Dittmar, Klaus J. Mattheier
Walter de Gruyter, 1988
Buku Referensi
Malmstrom, Jean
Hayden Book Company, 1965
Buku Teks
Bram, Joseph
Random House, 1955
Buku Teks