Arroyo, F., M. Alcalde, R. Villegas, and M. D. Robador. “Effect of the Diameter and Colour of Colorimeter Aperture Reducing Templates on Colour Coordinate Measurements”. Materiales De Construcción, vol. 58, no. 291, Sept. 2008, pp. 99-109, doi:10.3989/mc.2008.v58.i291.100.