| title | ISBN-13 (ISBN-10) | year of publica- tion | other author(s) |
|---|---|---|---|
| 50 Simple Steps to Save the Earth from Global Warming | 978-1-893910-49-2 (1-893910-49-0) | 2008 | David Steinman · R James Woolsey |
| 50 Simple Steps to Save the World's Rainforests: How to Save Our Rainforests Through Everyday Acts | 978-1-893910-60-7 (1-893910-60-1) | 2009 | Kim Henderson |