Leopold, Werner F., 1896-
Northwestern University, 1947
Buku Teks SO
Zamakhsyari Dhofier
LP3ES, 1990
Buku Teks
Artikel Jurnal
Endah H. Wulandari
University of Indonesia, Faculty of Humanities, 2003
Artikel Jurnal
edited by Paul Fletcher and Michael Garman
Cambridge University Press, 1986
Buku Teks