TY  - JOUR
AU  - D. B. Zot'ev
TI  - Contact degeneracies of closed  2-forms
JO  - Sbornik. Mathematics
PY  - 2007
SP  - 491
EP  - 520
VL  - 198
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SM_2007_198_4_a2/
LA  - en
ID  - SM_2007_198_4_a2
ER  -