Kuipers, Giselinde, author
De Gruyter Mouton, 2015
Buku Teks
edited by Chuang Lu and A.P. Li
John Wiley & Sons, 2010
eBooks
Artikel Jurnal
Katz, Alfred H., author
Third Party Publishing, 1990
Buku Teks
Ley, Willy, author
Doubleday and Company, Inc., 1969
Buku Teks