De Arithmetica - Boethius, Anicius Manlius Torquatus Severinus. (OLS)http://ftis/name/53847; Schilling, J. (OLS)http://ftis/name/68321; Oosthout, Henri. (OLS)http://ftis/name/68320 (Anicii Manlii Severini Boethii opera, 1999)