TY  - BOOK
AU  - Nemytskii, V.V.
AU  - Stepanov, V.V.
AU  - Lefschetz, Solomon. tr.
TI  - Qualitative theory of differential equations
T2  - Princeton mathematical series
U1  - 515.35 
PY  - 1960///
CY  - New Jersey
PB  - Princeton University Press
ER  -