* EPA Ireland (1997). [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.
* 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)