(en) [PDF] David M. Schaps, XIV International Economic History Congress, Helsinki, International Economic History Association, (lire en ligne), « The Invention of Coinage in Lydia, in India, and in China »
Sir Ralph Lilley Turner, « A Comparative Dictionary of the Indo-Aryan Languages », Includes three supplements, published 1969–1985., Digital South Asia Library, a project of the Center for Research Libraries and the University of Chicago, london: oxford university press, 1962–1966. (consulté le ) : « rū'pya 10805 rū'pya 'beautiful, bearing a stamp' ; 'silver' »
