Giorgi, J. (2009). Math for wastewater treatment operators grades 1 and 2: A guide to preparing for wastewater treatment operator certification exams. American Water Works Association.
Cita Chicago (17th ed.)Giorgi, John. Math for Wastewater Treatment Operators Grades 1 and 2: A Guide to Preparing for Wastewater Treatment Operator Certification Exams. Denver, Colo.: American Water Works Association, 2009.
Cita MLA (9th ed.)Giorgi, John. Math for Wastewater Treatment Operators Grades 1 and 2: A Guide to Preparing for Wastewater Treatment Operator Certification Exams. American Water Works Association, 2009.
Atenció: Aquestes cites poden no estar 100% correctes.