Maund, Alferd
University of Illinois Press , 1999
Buku Teks
Peranginangin, Bisman, author
1988
UI - Tesis (Membership)
Steward, Julian H.
Columbia University Press, 1973
Buku Teks
Allen, Frederick Lewis
Bantam Books, 1961
Buku Teks
Sobolev, Leonid, author
Moscow : Progress Publishers, 1965
Buku Teks