Ilford Ltd. Patent: US2704762 , 1953 ; Full Text Show Details Ilford Ltd. Patent: US2688024 , 1952 ; Full Text Show Details Duffin; Kendall Ind. chim. belge Sonderband 27.Congr. int. Chim. ind. Bruessel, 1954 , p. Bd. 3, S. 602