DOI:10.1038/nature.2014.14482. ↑ Например, в Farrar, John An Elementary Treatise on Arithmetic. ↑ Maher, David W.; Makowski, John F. Literary evidence for Roman arithmetic with fractions (инг.) // Classical Philology. — 2001. — № 4 (96). — P. 383. ↑ Leslie John The Philosophy of Arithmetic; Exhibiting a Progressive View of the Theory and Practice of Calculation, with Tables for the Multiplication of Numbers as Far as One Thousand — Edinburgh: Abernethy & Walker, 1820. ↑ Children must learn times tables by age nine… // Daily Mail, 17.12.2011 ↑ Роу С.