^ abcdCardarelli, F. (2003). Encyclopaedia of Scientific Units, Weights and Measures. Their SI Equivalences and Origins. London: Springer. p. 46. ISBN978-1-4471-1122-1.
^ abcdCardarelli, F. (2003). Encyclopaedia of Scientific Units, Weights and Measures. Their SI Equivalences and Origins. London: Springer. p. 49. ISBN978-1-4471-1122-1.