On the Sobolev Quotient of an Einstein Manifold Patricio AvilesJose Escobar Indiana University Mathematics Journal 1992 text pdf 10.1512/iumj.1992.41.41024 10.1512/iumj.1992.41.41024 en Indiana Univ. Math. J. 41 (1992) 435 - 438 state-of-the-art mathematics http://iumj.org/access/