Affine Maps on Tangent Bundles Mingxue Liu Indiana University Mathematics Journal 1974 text pdf 10.1512/iumj.1974.23.23050 10.1512/iumj.1974.23.23050 en Indiana Univ. Math. J. 23 (1974) 593 - 605 state-of-the-art mathematics http://iumj.org/access/