Filippov, S. B., and N. V. Naumova. “Axisymmetric Vibrations of Thin Shells of Revolution Joint at a Small Angle”. Technische Mechanik - European Journal of Engineering Mechanics, vol. 18, no. 4, Oct. 2019, pp. 285-90, https://journals.ub.ovgu.de/index.php/techmech/article/view/1175.