Urban, A. On the geometry of a system of partial differential equations of the second order. (English) Zbl 0035.24102 Proc. Akad. Wet. Amsterdam 52, 855-867 (1949); Indag. Math. 11, 303-315 (1949). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Keywords:Riemannian manifolds × Cite Format Result Cite Review PDF