The APA Style Blog instructs that:

If you are citing something that has been republished or reprinted, the entry in the reference list should use the date of the version you read. At the end, append the date of the original work or the source of the reprint (for details on how to format the reference see Example 21 on page 203 of the Publication Manual of the American Psychological Association, 6th edition). In text, cite both dates: first the original version, then the version you read, separated by a slash, for example: (Freud, 1900/1953).

(APA Style blog, accessed 29 Aug 2013)