Large Elastic Deformations of Homogeneous Anisotropic Materials Jerald EricksenR. Rivlin Indiana University Mathematics Journal 1954 text pdf 10.1512/iumj.1954.3.53014 10.1512/iumj.1954.3.53014 en Indiana Univ. Math. J. 3 (1954) 281 - 301 state-of-the-art mathematics http://iumj.org/access/