source:Source: https://www.researchgate.net/profile/Nana_Engo/publication/234034193_OPTIQUE_QUANTIQUE_2012-2013_MASTER_2_DE_PHYSIQUEUNIVERSITE_DE_NGAOUNDERE/links/02bfe50e6b5af3816d000000/OPTIQUE-QUANTIQUE-2012-2013-MASTER-2-DE-PHYSIQUE-UNIVERSITE-DE-NGAOUNDERE.pdf
