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4. Driver, R. D., A functional-differential system of neutral type arising in a two-body problem of classical electrodynamics. Internat. Sympos. Non-linear Differential Equations and Nonlinear Mechanics, pp. 474–484. New York: Academic Press 1963.
5. Driver, R. D., Existence theory for a delay-differential system. Contributions to Differential Equations 1, 317–336 (1963).