00711naa#a2200157#i#450# EN\\bibl\19043 20260122003927.4 20251230b2025####ek#y0engy0150####ca RU GEOMETRIC METHOD FOR ANALYZING THE EXISTENCE OF A PERIODIC SOLUTION TO A DIFFERENTIAL EQUATION Conference article/thesis Voronezh FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov 2025 5 с. Conference article/thesis local Линейные обыкновенные дифференциальные уравнения и системы. 517.926 Korotkih A. S. bibl.vgltu.ru