BOGDANSKII, Yu. V. Boundary Trace Operator in a Domain of Hilbert Space and the Characteristic Property of its Kernel. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 11, p. 1450–1460, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2081. Acesso em: 5 dec. 2025.