BIKULČIENĖ, Liepa. Realization of operator expressions for the solutions of differential equations. Lietuvos matematikos rinkinys, [S. l.], v. 42, n. spec., p. 159–164, 2002. DOI: 10.15388/LMR.2002.32850. Disponível em: https://www.journals.vu.lt/LMR/article/view/32850.. Acesso em: 9 may. 2024.