κοινών
From LSJ
μεγάλα ὠφελήσεσθε πρὸς ἱστορίαν τῶν κοινῶν → that will be of great benefit to you in order to understand public affairs
English (LSJ)
ῶνος, ὁ, Dor., Arc.κοινάν, ᾶνος (q.v.),
A = κοινωνός, which is much more freq., X.Cyr.7.5.35, 8.1.16, 36, 40; of partners in a tax-farming syndicate, PRev.Laws 10.10, al. (iii B.C.).