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A two point boundary value problem with jumping nonlinearities. Proc. Amer. Math. Soc. 79 (1980), 207-211.
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Topological Degree Methods in Nonlinear Boundary Value Problems. Regional Confer. Series in Math. n° 40, Amer. Math. Soc., Providence, 1979.
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Asymptotic conditions for periodic solutions of ordinary differential equations. Proc. Amer. Math. Soc. 81 (1981), 415-420.
MR 0597653 |
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Existence for a class of semilinear problems at resonance. J. Differential Equations 45 (1982), 156-167.
MR 0665993 |
Zbl 0515.34003