* [https://www.epa.ie/pubs/advice/water/wastewater/wastewatertreatmentmanuals-primarysecondarytertiarytreatment.html EPA Ireland (1997). Waste Water Treatment Manuals – Primary, Secondary and Tertiary Treatment]. Wexford, IE.:Available at: [http://www.epa.ie epa.ie]
* Tchobanoglous, G., Burton, F. L. and Stensel, H. D. (2004). Wastewater Engineering: Treatment and Reuse, Metcalf & Eddy, 4th Ed. (Internat. Ed.). McGraw-Hill, New York, US.(Book)