Freeman and Company, New York, NY ISBN 0-7167-1020-X# Standard Methods for the Examination of Water and Wastewater - 20th Edition ISBN 0-87553-235-7.
Freeman and Company, New York, NY ISBN 0-7167-1020-X* "Standard Methods for the Examination of Water and Wastewater" – 20th Edition ISBN 0-87553-235-7.