(subclass MustardGas BlisterAgent) | WMD.kif 492-492 | Mustard gas is a subclass of blister agent |
(subclass SulphurMustardGas MustardGas) | WMD.kif 498-498 | Sulphur mustard gas is a subclass of mustard gas |
(subclass NitrogenMustardGas MustardGas) | WMD.kif 503-503 | Nitrogen mustard gas is a subclass of mustard gas |