S. Soulayman, M. Alhelou and W. Sabbagh  2016. All-World Solar Collector Optimum Slope Determination Basing on Site Latitude and Day Number. Journal of Solar Energy Research Updates. 3, 1 (Sep. 2016), 1–12. DOI:https://doi.org/10.15377/2410-2199.2016.03.01.1.