Hexagon head bolts, screws and nuts of product grades A and B: Part 5 hexagon thin nuts - Product grade B (Unchamfered) (Size Range M 1.6t0 M 10) (Fourth Revision)
Technical supply conditions for threaded steel fasteners: Part 2 tolerances for fasteners - Bolts, screws, studs and nuts - Product grades a, b and c (Third Revision)