Hobbs, Jack A.
Harcourt Brace Jovanovich, 1980
Buku Teks
Blaser, Werner, 1924-, author
Birkhauser, 1999
Buku Teks
Institute for Alternative Futures, 1983
Buku Teks
Hobbs, Lisa
McGraw-Hill, 1967
Buku Teks
De Vido, Alfredo, author
Wiley, 1996
Buku Teks