Acts 1965, 59th Leg., vol. 2, p. 317, ch. 722. Amended by Acts 1973, 63rd Leg., p. 977, ch. 399, Sec. 2(C), eff. Jan. 1, 1974; Acts 1973, 63rd Leg., p. 1251, ch. 454, art. 2, Sec. 1, eff. Jan. 1, 1974.

Amended by Acts 1981, 67th Leg., p. 2239, ch. 534, Sec. 1, eff. Aug. 31, 1981.