Doan, Tran Van
The council for research in values and philosophy , 2000
Buku Teks
edited by John N. Gardner and A. Jerome Jewler
Wadsworth, 1985
Buku Teks
with a pref. by Robert S. McNamara
The John Hopkins University Press , 1975
Buku Teks
Coombs, Philip H.
Johns Hopkins University Press, 1974
Buku Teks
Coombs, Philip H.
John Hopkins University Press, 1988
Buku Teks