EI-Sayed, A. and Shaaban, M. 1999. Monthly Monitoring of the Nutrient Status in Citrus Leaves as a Guide for Proper Fertilization. Journal of Agricultural and Marine Sciences [JAMS]. 4, 1 (Jan. 1999), 17–22. DOI:https://doi.org/10.24200/jams.vol4iss1pp17-22.