Shushkevich, G., S. Shushkevich, and F. Stachowicz. “The Scattering of the Sound Field by Thin Unclosed Spherical Shell and Ellipsoid”. Advances in Mechanical and Materials Engineering, Vol. 33, no. 293 (2), July 2016, pp. 167-81, doi:10.7862/rm.2016.14.