F. Benford (1938). The law of anomalous numbers. Proceedings of the American Philosophical Society, 78:127-131.
T. Hill (1995). The significant-digit phenomenon. The American Mathematical Monthly, 102(4):322-327. 10.2307/2974952.
R. Newcomb (1881). Note on the frequency of use of the different digits in natural numbers. American Journal of Mathematics, 4:39-40. 10.2307/2369148.