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