O'Connor, J.J. and Robertson, E.F. 2000. 'Indian Numerals'Archiviato il 29 settembre 2007 in Internet Archive., MacTutor History of Mathematics Archive, School of Mathematics and Statistics, University of St. Andrews, Scotland.
web.archive.org
O'Connor, J.J. and Robertson, E.F. 2000. 'Indian Numerals'Archiviato il 29 settembre 2007 in Internet Archive., MacTutor History of Mathematics Archive, School of Mathematics and Statistics, University of St. Andrews, Scotland.