Here are some source texts and comments.
1. J. Barnes, ed., "The Complete Works of Aristotle," Princeton, NJ:
Princeton University Press, vols. I & II, 1984. [Standard edition of
Aristotle in English. The translation of "On Sophistical Refutations"
is by W.A. Pickard-Cambridge.]
2. E.S. Forster, trans., "Aristotle: On Sophistical Refutations," in
vol. III (of XXIII) of the Loeb Aristotle series, Cambridge: Harvard
Univ. Press, 2000. [Greek text and Forster's translation into English
on facing pages. Contains a short introduction, footnotes, and
cross-references.]
3. Pickard-Cambridge's translation is online in several places, among
them:
(a)
http://www.greektexts.com/library/Aristotle/On_Sophistical_Refutations/eng/857.html
(b) http://classics.mit.edu/Aristotle/sophist_refut.html
--Ron Allen