Salam A Elementary Particle Theory. Proc. 8th Nobel Symp., 19 - 25 May 1968, Lerum, Sweden (Ed.NSvartholm) (New York: Wiley, Stockholm: Almqvist and Wiksell, 1968) p. 367
Lee B W Proc. of the 16th Intern. Conf. on High-Energy Physics, 6 - 13 September 1972, Batavia, Ill., USA (Eds J D Jackson, A Roberts) (Menlo Park, CA: SLAC, 1972)