Acts 1965, 59th Leg., vol. 2, p. 317, ch. 722. Amended by Acts 1967, 60th Leg., p. 1733, ch. 659, Sec. 2, eff. Aug. 28, 1967; Acts 1971, 62nd Leg., p. 3028, ch. 996, Sec. 1, eff. June 15, 1971; Acts 1973, 63rd Leg., p. 1127, ch. 426, art. 3, Sec. 5, eff. June 14, 1973.

Amended by Acts 1991, 72nd Leg., ch. 652, Sec. 3, eff. Sept. 1, 1991.