Bower, R., Lucey, J., & Ellis, R. (1992). Precision Photometry of Early Type Galaxies in the Coma and Virgo Clusters - a Test of the Universality of the Colour / Magnitude Relation - Part Two - Analysis. Monthly Notices of the Royal Astronomical Society, 254(4), 601-613. https://doi.org/10.1093/mnras/254.4.601