Giddings, J. Calvin
John Wiley & Sons, 1991
Buku Teks
edited by Otto Neurath, Rudolf Carnap and Charles Morris
University of Chicago Press, 1955
Buku Referensi
Finster, Felix, editor
[Springer, ], 2012
eBooks
Williams, Malcolm, 1953-
Routledge, 2000
Buku Teks
Hicks, John R.
The Clarendon Press, 1952
Buku Teks