Govier, Trudy
Wadsworth, 1985
Buku Teks
Barker, S. F.
Cornell University Press, 1957
Buku Teks
Pratt, Scott L
Wiley, 2015
Buku Teks
Carnap, Rudolf, author
Phoenix Books, 1947
Buku Teks
edited by Witold Marciszewski
Martinus Nijhoff Publishers, 1981
Buku Referensi