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Fowler, A.C. and C. Sparrow 1991 Bifocal homoclinic orbits in four dimensions (with C. Sparrow). Nonlinearity 4, 1159-1182.
Fowler, A.C. and C. Sparrow 1991 Bifocal homoclinic orbits in four dimensions (with C. Sparrow). Nonlinearity 4, 1159-1182.