1. Gaertner AA. In: Cocco L, editor. Optical Radiation Measurement, Modern Metrology Concerns. Croatia: InTech; 2012 Available from: http://www.intechopen.com/books/modern-metrologyconcerns/optical-radiation-measurements. ISBN: 978-953-51-0584-8
2. CIE. The Basis of Physical Photometry. 3rd Edition, PUBLICATION No 18.2 (TC-I .2) ISBN: 92-9034-01 8-5 ed. Vienna, Austria: Commission Internationale deL’Eclairage; 1983
3. https://www.slideshare.net/OSRAMLEDlight/osram-os-led Fundamentals radiometry photometry v281111
4. CIE: 1987, International Lighting Vocabulary”, Publication No 17.4, Commission Internationale deL’Eclairage, Vienna, Austria.
5. https://spie.org/publications/fg11_p02_solid_angle?SSO=1