.Langley, B. C. (1991). High-Efficiency gas furnace troubleshooting handbook. Prentice-hall, Inc.
Citación estilo Chicago.Langley, Billy C. High-Efficiency Gas Furnace Troubleshooting Handbook. New jersey: Prentice-hall, Inc, 1991.
Cita MLA.Langley, Billy C. High-Efficiency Gas Furnace Troubleshooting Handbook. Prentice-hall, Inc, 1991.
Warning: These citations may not always be 100% accurate.