The headword is present middle infinitive of periora/w, probably not extracted from any text but chosen as an unmarked lemma form, as is usual for Aelius Dionysius (see n. 1). The forms in the quotations that follow are all middle participles of the same verb.
[1] = Aelius Dionysius pi38 and Photius pi724 Theodoridis, but here with some errors and omissions. The first quotation is an amalgamation of two quotations in the original (the fault line indicated by the ellipsis) occasioned by haplographic omission of one of the two instances of periorwme/nous. The quotations combined here are Thucydides 4.73.1 ("and the Megarians keeping watch over which side would win"), and a quotation that does not actually occur in Thucydides but might, as Adler and Theodoridis suggest, be a loose version of 2.43.4 (Pericles in the Funeral Speech urges his fellow-citizens not to dwell on the dangers of war: mh\ periora=sqai tou\s polemikou\s kindu/nous). The second is a (faulty) quotation of Thucydides 4.124.4; in the original Brasidas is keeping watch over Mende (th=s *me/ndhs rather than over the battle (th=s ma/xhs). This error is not present in Aelius Dionysius or Photius.
[2] An approximation of Cassius Dio 51.24.1.