3-Cyano-2-nitro-6-(trifluoromethoxy)pyridine-4-carboxylic acid
3-Chloro-2-nitro-6-(trifluoromethoxy)pyridine-4-carboxylic acid
3-Cyano-2-nitro-4-(trifluoromethoxy)pyridine-6-carboxylic acid
2-Chloro-6-nitro-3-(trifluoromethoxy)pyridine-5-carboxylic acid