@article{01246363,
title = {Linear Pfaff systems with the lower characteristic vectors' set of positive Lebesgue measure.},
journal = {Memoirs on Differential Equations and Mathematical Physics},
volume = {15},
year = {1998},
pages = {136-139},
zbl = {0918.35037},
language = {en},
url = {http://dml.mathdoc.fr/item/01246363}
}
Izobov, N. Linear Pfaff systems with the lower characteristic vectors' set of positive Lebesgue measure.. Memoirs on Differential Equations and Mathematical Physics, Tome 15 (1998) pp. 136-139. http://gdmltest.u-ga.fr/item/01246363/