CIBA Patent: DE582319 , 1930 ; Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 19, p. 1141 Full Text Show Details CIBA Patent: US1881236 , 1930 ; Full Text Show Details Olin Mathieson Chem. Corp. Patent: US2713049 , 1953 ;