| title | ISBN-13 | year of publication |
|---|---|---|
| Math for Distribution System Operators: Practice Problems to Prepare for Distribution System Operator Certification Exams | 978-1-58321-455-8 | 2007 |
| Math for Wastewater Treatment Operators Grades 1 & 2: Practice Problems to Prepare for Wastewater Treatment Operator Certification Exams | 978-1-58321-587-6 | 2009 |
| Math for Water Treatment Operators: Practice Problems to Prepare for Water Treatment Operator Certification Exams | 978-1-58321-454-1 | 2007 |
| Operator Certification Study Guide, Fifth Edition | 978-1-58321-287-5 | 2003 |
| Wastewater Operator Certification Study Guide | 978-1-58321-728-3 | 2009 |
| Water Operator Certification Study Guide: A Guide to Preparing for Water Treatment and Distribution Operator Certification Exams | 978-1-58321-852-5 | 2011 |