KIRJACKIS, Eduardas. On some properties of Schwartz–Gopengauz operator. Lietuvos matematikos rinkinys, [S. l.], v. 46, n. spec., p. 41–47, 2023. DOI: 10.15388/LMR.2006.30569. Disponível em: https://www.journals.vu.lt/LMR/article/view/30569.. Acesso em: 17 may. 2024.