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Elementary Problems: E2057, E2085-E2094R. S. Luthar, J. H. Butchart, Beatriz Margolis, H. E. Chrestenson, J. F. Randolph, J. C. Brooks, J. O. Kiltinen, T. J. Grilliot, A. Domergue, Erwin Just and Norman Schaumberger · The American Mathematical Monthly · 1968