Abdallah, Khaled Zaher, and Gina Hammam. 2014. “Correlation Between Biochemical Oxygen Demand and Chemical Oxygen Demand for Various Wastewater Treatment Plants in Egypt to Obtain the Biodegradability Indices”. International Journal of Sciences: Basic and Applied Research (IJSBAR) 13 (1):42-48. https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/1382.