DOLPH, C. L. Positive real resolvents and linear passive Hilbert systems. Annales Fennici Mathematici, [S. l.], n. 336/9, 1964. DOI: 10.5186/aasfm.1964.336-09. Disponível em: https://afm.journal.fi/article/view/134031. Acesso em: 26 nov. 2024.