1. W.G.Adouns, and R.E.Day, V. The action of light on selenium, Proc Roy. Soc. A25 (1877)113-117. http://doi.org/10.1098/rspl.1876.0024.
2. https://en.wikipedia.org/wiki/Timeline_of_solar_cells.
3. New photoelectric cell;Lange;Zeit Phys.,1930
4. L.O.Grondahl, The Copper-Cuprous-Oxide Rectifier and Photoelectric Cell, Rev. Mod. Phys.