Colour vision deficiencies IX : proceedings of the ninth symposium of the International Research Group on Colour Vision Deficiencies, held at St. John's College, Annapolis, Maryland, U.S.A., 1-3 July 1987 / ed. by B. Drum and G. VerriestColor vision deficiencies : proceedings of the Symposium of the International Research Group on Color Vision Deficiencies, Tokyo, Japan, March 26-28, 1990 / ed. by Y. OhtaColour vision deficiencies XI : proceedings of the eleventh symposium of the International Research Group on Colour Vision Deficiencies, held in Sydney, Australia, 21-23 June 1991, including a joint IRGCVD-AIC meeting on mechanisms of colour vision, 24 June 1991 / ed. by B. DrumColour vision deficiencies XII : proceedings of the twelfth symposium of the International Research Group on Colour Vision Deficiencies, held in Tübingen, Germany, July 18-22, 1993 / ed. by B. Drum ; with associate ed.: A.J. Adams ... [et al.]Colour vision deficiencies XIII : proceedings of the thirteenth symposium of the International Research Group on colour vision deficiencies, held in Pau, France, July 27-30, 1995 / ed. by C.R. Cavonius ; with associate eds.: A.J. Adams ... [et al.]Colour vision deficiencies VI : proceedings of the sixth Symposium of the International Research Group on Colour Vision Deficiencies held at the Klinikum der Freien Universität, (West) Berlin-Steglitz, 17-19 September 1981 / ed. by G. VerriestColour vision deficiencies VIII : proceedings of the eighth symposium of the International Research Group on Colour Vision Deficiencies, held at the Palais des Papes, Avignon, France, 23-26 June 1985 / ed. by G. Verriest