Helgason, Sigurdur Remarque sur R. G. McLenaghan: On the validity of Huygens principle for second order partial differential equations with four independent variables. I. (English) Zbl 0304.35063 Ann. Inst. Henri Poincaré, Nouv. Sér., Sect. A 21(1974), 347 (1975). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 1 Document MSC: 35L05 Wave equation × Cite Format Result Cite Review PDF Full Text: Numdam EuDML