| title | media type | ISBN-13 | year of publication |
|---|---|---|---|
| The Environmental Crisis | Hardcover | 978-0-300-01432-7 | 1971 |
| The Environmental crisis | " | 978-0-300-01312-2 | 1970 |
| The Environmental crisis | Paperback | 978-0-300-01433-4 | 1970 |
| THE ENVIRONMENTAL CRISIS Man's Struggle to Live with Himself . | " | 978-0-300-01313-9 | 1970 |
H.H. · H.W. · Harold W · W H · W. Helfrich