Levinson, Norman On the existence of periodic solutions for second order differential equations with a forcing term. (English) Zbl 0061.18909 J. Math. Phys. 22, 41-48 (1943). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 35 Documents Keywords:ordinary differential equations, difference equations × Cite Format Result Cite Review PDF Full Text: DOI