BIGUN, Ya. I. Averaging of a multifrequency boundary-value problem with linearly transformed argument. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 3, p. 291–299, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4419. Acesso em: 5 dec. 2025.