Meister, Darryl (12 April 2010). Understanding reference wavelengths(PDF). opticampus.opti.vision (memo). Carl Zeiss Vision. Archived(PDF) from the original on 2022-10-09. Retrieved 2013-03-13.
glassproperties.com
Fluegel, Alexander (2007-12-07). "Abbe number calculation of glasses". Statistical Calculation and Development of Glass Properties (glassproperties.com). Retrieved 2022-01-16.
opti.vision
opticampus.opti.vision
Meister, Darryl (12 April 2010). Understanding reference wavelengths(PDF). opticampus.opti.vision (memo). Carl Zeiss Vision. Archived(PDF) from the original on 2022-10-09. Retrieved 2013-03-13.