University of Minneapolis Press, 1975
Buku Teks
Elder, Neil C.M.
Pergamon Press , 1970
Buku Teks
Gullander, Ake
The Iowa State College Press, 1951
Buku Teks
Gustafsson, Agne
Swedish Institute, 1983
Buku Teks
Boalt, Gunnar, author
John Wiley & Sons, 1970
Buku Teks