^Iwata, Shigeo (2008), "Weights and Measures in the Indus Valley", Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures (2nd edition) edited by Helaine Selin, pp. 2254–2255, Springer, ISBN978-1-4020-4559-2.
^Kenoyer, Jonathan Mark (2006), "Indus Valley Civilization", Encyclopedia of India (vol. 2) edited by Stanley Wolpert, pp. 258–266, Thomson Gale, ISBN0-684-31351-0
^In the third millennium BCE the Indus measuring system was further developed in the ancient regions of Iran and Afghanistan -- Iwata, 2254.