Poznyak, E. G.; Popov, A. G. Non-Euclidean geometry: The Gauss formula and an interpretation of partial differential equations. (English) Zbl 0852.35128 J. Math. Sci., New York 78, No. 3, 241-252 (1996). MSC: 35Q53 53A35 PDFBibTeX XMLCite \textit{E. G. Poznyak} and \textit{A. G. Popov}, J. Math. Sci., New York 78, No. 3, 241--252 (1996; Zbl 0852.35128) Full Text: DOI
Poznyak, Eh. G.; Popov, A. G. The geometry of the sine-Gordon equation. (English. Russian original) Zbl 0835.35123 J. Math. Sci., New York 70, No. 2, 1666-1684 (1994); translation from Itogi Nauki Tekh., Ser. Probl. Geom. 23, 99-130 (1991). MSC: 35Q53 53C45 PDFBibTeX XMLCite \textit{Eh. G. Poznyak} and \textit{A. G. Popov}, J. Math. Sci., New York 70, No. 2, 1666--1684 (1994; Zbl 0835.35123); translation from Itogi Nauki Tekh., Ser. Probl. Geom. 23, 99--130 (1991) Full Text: DOI