Source: https://www.researchgate.net/profile/Salem-Kahlouche/publication/267413478_Prediction_d'orbite_de_satellite_a_basse_altitude_et_geostationnaire_par_la_methode_de_RUNGE_KUTTA/links/596f4dadaca2722710136108/Prediction-dorbite-de-satellite-a-basse-altitude-et-geostationnaire-par-la-methode-de-RUNGE-KUTTA.pdf