References
- Van DusenH. A.Jr., “Street Lighting Luminaire Dirt Depreciation”, Illuminating Engineering, Vol. 66, February 1971, p. 122.
- “IES Approved Method for Determining Luminaire-Lamp-Ballast Combination Operating Factors for High Intensity Discharge Luminaires”, Illuminating Engineering, Vol. 65, December 1970, p. 718.