Bauer. Nouvelles annales2, 256-264, 1902.Hardy, G. H. and Wright, E. M. J. London Math. Soc.9, 38-41 and 240, 1934.Hardy, G. H. and Wright, E. M. "Bauer's Identical Congruence." §8.5 in An Introduction to the Theory of Numbers, 5th ed. Oxford, England: Clarendon Press, pp. 98-100, 1979.Sloane, N. J. A. Sequence A158008 in "The On-Line Encyclopedia of Integer Sequences."