TY  - JOUR
AU  - M. B. Karmanova
TI  - Two-step sub-Lorentzian structures and graph surfaces
JO  - Izvestiya. Mathematics 
PY  - 2020
SP  - 52
EP  - 94
VL  - 84
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_2020_84_1_a3/
LA  - en
ID  - IM2_2020_84_1_a3
ER  -