*L V Morrison, F R Stephenson (2004), "Historical values of the Earth's clock error ΔT and the calculation of eclipses", "Journal for the History of Astronomy" (ISSN 0021-8286), vol.
* L V Morrison, F R Stephenson (2004), «Historical values of the Earth’s clock error ΔT and the calculation of eclipses», "Journal for the History of Astronomy" (ISSN 0021-8286), vol.