(subclass PetroleumLubricant RefinedPetroleumProduct) | Economy.kif 5935-5935 | PetroleumLubricant e' uma sub-classe de RefinedPetroleumProduct |
(subclass MotorOil PetroleumLubricant) | Economy.kif 5939-5939 | MotorOil e' uma sub-classe de PetroleumLubricant |