A Uniqueness Theorem of Bernstein's Type for Minimal Surfaces in Cylindrical Coordinates Joachim Nitsche Indiana University Mathematics Journal 1957 text pdf 10.1512/iumj.1957.6.56048 10.1512/iumj.1957.6.56048 en Indiana Univ. Math. J. 6 (1957) 859 - 864 state-of-the-art mathematics http://iumj.org/access/