00652naa#a2200193#i#450# EN\\bibl\2829 20250501010037.4 2308-8877 20140616b2014####ek#y0engy0150####ca RUS RU On the number invariant line of planar polynomial differential systems from above estimate Journal article Voronezh FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov 2014 3 с. Journal article local Ushkho A. Tlyachev V. Ushkho D. anni.editorum.ru