Cita APA (7th ed.)

Hartwell, F. P. (2021). McGraw-Hill's national electrical code 2020 handbook (Thirtieth edition.). McGraw Hill.

Cita Chicago (17th ed.)

Hartwell, Frederic P. McGraw-Hill's National Electrical Code 2020 Handbook. Thirtieth edition. New York: McGraw Hill, 2021.

Cita MLA (9th ed.)

Hartwell, Frederic P. McGraw-Hill's National Electrical Code 2020 Handbook. Thirtieth edition. McGraw Hill, 2021.