Błocka, B. “Free Vibrations of Thin, Elastic, Orthogonally Stiffened Shells of Revolution With Stiffeners Treated As Discrete Elements”. Engineering Transactions 37, no. 1 (March 31, 1989): 65–87. Accessed January 17, 2026. http://et.ippt.gov.pl/index.php/et/article/view/1656.