In 1964, Salam and John Ward published a combined theory of the electromagnetic and weak forces that, like the one Glashow published in 1961, had SU(2)×U(1) as the gauge group. These attempts to model a unified electroweak force did not fully succeed, because they did not account for the contrast between the massive gauge bosons of the weak force and the massless gauge boson of the electromagnetic force. In 1967, Steven Weinberg found the desired unification by using the idea of spontaneous symmetry breaking to explain the mass asymmetry of the four electroweak gauge bosons. In 1968, half a year after Weinberg’s paper had appeared in print, Salam, writing without his previous coauthor Ward, incorporated spontaneous symmetry breaking into the Salam- Wardmodel and arrived somewhere near the same point as Weinberg, who alone had considered the masses of the W± and Z0 bosons.