publication venue for ISOMETRIC EMBEDDING VIA STRONGLY SYMMETRIC POSITIVE SYSTEMS 2018 TOTALLY QUASI-UMBILIC TIMELIKE SURFACES IN R-1,R-2 2012 BACKLUND TRANFORMATIONS AND DARBOUX INTEGRABILITY FOR NONLINEAR WAVE EQUATIONS 2009 Geometry of sub-Finsler Engel manifolds 2007 Homogeneous Bäcklund transformations of hyperbolic Monge–Ampère systems 2002 The generalized Chazy equation and Schwarzian triangle functions 1998