Zeller, Eduard, 1814-1908
Outlines of the history of Greek philosophy
Meridian Books, 1960
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Armstrong, A.H.
An introduction to ancient philosophy
Newman Press, 1949
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Oxford studies in ancient philosophy; Vol.III
edited by Julia Annas
Clarendon Press , 1985
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Burnet, John
Early Greek philosophy. / John Burnet
Meridian Books, 1957.
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Oxford studies in ancient philosophy; Vol. II
edited by Julia Annas
Clarendon Press, 1984
 Buku Teks