Cornell University Library · Routledge
| title | ISBN-13 | year of publication |
|---|---|---|
| A Philosopher With Nature: -1921 | 978-1-112-30147-6 | 2009 |
| A Philosopher with Nature | 978-1-138-18763-4 | 2015 |
| Principles of Western Civilisation | 978-1-112-01770-4 | 2009 |
| Social Evolution | 978-1-112-00710-1 | 2009 |