Source: https://www.researchgate.net/profile/Frederic-Elie-2/publication/317039535_Loi_de_l'emission_du_rayonnement_loi_de_Planck_une_demonstration_quantique/links/5921f0370f7e9b9979443f0e/Loi-de-lemission-du-rayonnement-loi-de-Planck-une-demonstration-quantique.pdf