ALEXANDROV, E, and A HEBBECHE. “FONCTIONS SPECTRALES D’UNE CERTAINE CLASSE D’OPERATEURS SYMETRIQUES”. Sciences & Technology. A, exactes sciences, no. 17 (June 1, 2002): 7–10. Accessed July 3, 2024. https://revue.umc.edu.dz/a/article/view/1777.