National Fire Protection Association. (2020). NFPA 497: Recommended practice for the classification of flammable liquids, gases, or vapors and of hazardous (classified) locations for electrical installations in chemical process areas. 2021 Edition (1 edición.). Massachusetts, Estados Unidos: National Fire Protection Association (NFPA).
Citación estilo ChicagoNational Fire Protection Association. NFPA 497: Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas. 2021 Edition. 1 edición. Massachusetts, Estados Unidos: National Fire Protection Association (NFPA), 2020.
Cita MLANational Fire Protection Association. NFPA 497: Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas. 2021 Edition. 1 edición. Massachusetts, Estados Unidos: National Fire Protection Association (NFPA), 2020.