Gen. Aniline Works Patent: US1900426 , 1929 ; Full Text Show Details I.G. Farbenind. Patent: DE511526 , 1929 ; Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 17, p. 456,457 Full Text Show Details I.G. Farbenind. Patent: DE512722 , 1929 ;