1. ICI, BP 785,120; 785,222 (29.11.1954).
2. ICI, DAS 1,075,245 (30.1.1957) BASF, FR 1,194,043 (5.4.1957); S, DAS 1,258,526 (29.11.1957).
3. BASF, DAS 1,056,580 (14.12.1957).
4. FBy, DAS 1,186,160 (7.2.1961).
5. “Recent Progress in the Chemistry of Natural and Synthetic Colouring Matters and Related Fields”;Heyna,1962