Hospers, John, author
Roudledge, 1988
Buku Teks
Helmut Wautischer
Springer, 2012
eBooks
Chamberlain, John Martyn, author
[Springer, ], 2013
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Roscoe, Lori A., author
Springer Nature, 2017
eBooks
Grayling, A. C.
Blackwell Publishers, 1997
Buku Teks