• [1] Earl A. Coddington and Norman Levinson, Theory of ordinary differential equations, McGraw-Hill Book Company, Inc., New York-Toronto-London, 1955. MR 0069338
• [2] L. Flatto and N. Levinson, Periodic solutions of singularly perturbed systems, J. Rational Mech. Anal. 4 (1955), 943–950. MR 0076126
• [3] K. O. Friedrichs and W. R. Wasow, Singular perturbations of non-linear oscillations, Duke Math. J. 13 (1946), 367–381. MR 0018308
• [4] I. S. Gradšteĭn, On a class of nonlinear differential equations with small coefficients for certain derivatives, Doklady Akad. Nauk SSSR (N.S.) 64 (1949), 441–443 (Russian). MR 0029033
• [5] J. J. Levin, Singular perturbations of nonlinear systems of differential equations related to conditional stability, Duke Math. J. 23 (1956), 609–620. MR 0080809
• [6] J. J. Levin and Norman Levinson, Singular perturbations of non-linear systems of differential equations and an associated boundary layer equation, J. Rational Mech. Anal. 3 (1954), 247–270. MR 0061241
• [7] A. N. Tihonov, On systems of differential equations containing parameters, Mat. Sbornik N.S. 27(69) (1950), 147–156 (Russian). MR 0036902

Bibliography

[1]

E. A. Coddington and N. Levinson, Theory of ordinary differential equations, New York, 1955. MR 0069338 (16:1022b)

[2]

L. Flatto and N. Levinson, Periodic solutions of singularly perturbed systems, Journal of Rational Mechanics and Analysis vol. 4 (1955) pp. 943-950. MR 0076126 (17:849h)

[3]

K. O. Friedrichs and W. R. Wasow, Singular perturbation of non-linear oscillations, Duke Math. J. vol. 13 (1946) pp. 367-381. MR 0018308 (8:272d)

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I. S. Gradstein, On a class of non-linear differential equations with small coefficients for certain derivatives, Doklady Akademii Nauk SSSR. (N.S.) vol. 64 (1949) pp. 441-443. MR 0029033 (10:536c)

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J. J. Levin, On singular perturbations of nonlinear systems of differential equations related to conditional stability, Duke Math. J. vol. 24 (1956) pp. 609-620. MR 0080809 (18:305f)

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J. J. Levin and N. Levinson, Singular perturbations of non-linear systems of differential equations and an associated boundary layer equation, Journal of Rational Mechanics and Analysis vol. 3 (1954) pp. 247-270. MR 0061241 (15:795f)

[7]

A. Tihonov, On systems of differential equations containing parameters, Rec. Math. (Mat. Sbornik) N.S. vol. 27 (69) (1950) pp. 147-156 MR 0036902 (12:181d)