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