A Central Limit Theorem for Non-Linear Functions of a Normal Stationary Process Tze-Chien Sun Indiana University Mathematics Journal 1963 text pdf 10.1512/iumj.1963.12.12066 10.1512/iumj.1963.12.12066 en Indiana Univ. Math. J. 12 (1963) 945 - 977 state-of-the-art mathematics http://iumj.org/access/