Commentary on: [L 29] Transformation Theory of Non-Linear Differential Equations of the Second Order [L 38] A Second Order Differential Equation with Singular Solutions [L 47] Small Periodic Perturbations of an Autonomous System with a Stable Orbit
1931 ◽
Vol 27
(4)
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pp. 546-552
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1951 ◽
Vol 3
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pp. 335-338
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1955 ◽
Vol 51
(4)
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pp. 604-613
2018 ◽
Vol 12
(2)
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pp. 481-492
2020 ◽
Vol 8
(3)
◽
pp. 61-68
1977 ◽
Vol 77
(3-4)
◽
pp. 309-318
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