^See, for example, the Merriam-Webster's Collegiate Dictionary, the American Heritage Dictionary, and the Oxford English Dictionary.
^International Astronomical Union (编), RESOLUTION B2 on the re-definition of the astronomical unit of length(PDF), RESOLUTION B2, Beijing, Kina: International Astronomical Union, 31 August 2012 [2017-03-15], (原始内容存档(PDF)于2013-08-16), The XXVIII General Assembly of International Astronomical Union recommends [adopted] that the astronomical unit be re-defined to be a conventional unit of length equal to exactly 7011149597870700000♠149597870700 metres, in agreement with the value adopted in IAU 2009 Resolution B2