The Maximum Modulus Principle, I. Necessary Conditions David EllisC. HillChester Seabury Indiana University Mathematics Journal 1976 text pdf 10.1512/iumj.1976.25.25055 10.1512/iumj.1976.25.25055 en Indiana Univ. Math. J. 25 (1976) 709 - 715 state-of-the-art mathematics http://iumj.org/access/