On Axially Symmetric Stress Distributions in Solids under Torsion Containing Spherical Cracks and Cavities R. Shail Indiana University Mathematics Journal 1965 text pdf 10.1512/iumj.1965.14.14012 10.1512/iumj.1965.14.14012 en Indiana Univ. Math. J. 14 (1965) 143 - 160 state-of-the-art mathematics http://iumj.org/access/