Interior Gradient Estimates for Solutions of Prescribed Curvature Equations of Parabolic Type Bo GuanJoel Spruck Indiana University Mathematics Journal 1991 text pdf 10.1512/iumj.1991.40.40066 10.1512/iumj.1991.40.40066 en Indiana Univ. Math. J. 40 (1991) 1471 - 1481 state-of-the-art mathematics http://iumj.org/access/