Hazard, C.; Mackey, M. B.; Shimmins, A. J. «Investigation of the Radio Source 3C273 by the method of Lunar Occultations». Nature, vol. 197, 4872, 1963, pàg. 1037. Bibcode: 1963Natur.197.1037H. DOI: 10.1038/1971037a0.
Hazard, C.; Mackey, M. B.; Shimmins, A. J. «Investigation of the Radio Source 3C273 by the method of Lunar Occultations». Nature, vol. 197, 4872, 1963, pàg. 1037. Bibcode: 1963Natur.197.1037H. DOI: 10.1038/1971037a0.
Jean Meeus, "La périodicité des occultations", Ciel et Terre, 87 (1971), 240–252 ADS link – English translation in: Jean Meeus, "Series of occultations", in: Mathematical Astronomy Morsels (Richmond: Willmann-Bell, 1997), pp.113–124.