that is his Theorem 1. write the cup-1 product x cup_1 y as xy. his Theorem 2 is (xy)z + x(yz) + (xz)y + x(zy) = 0 mod 2; it's plausible that there's a version of this with appropriate signs over Z, but i don't want to compute the signs. his Theorem 3 is the observation on symmetric Massey products mod 2 (later reproduced by others): if x cup y = 0, then <x,y,x> = y cup Sq_{n-1}(x) mod the ideal (x).