| title | ISBN-13 (ISBN-10) | year of publica- tion | other author(s) |
|---|---|---|---|
| Second Nature: Enviromental Enrichment for Captive Animals | 978-1-56098-397-2 (1-56098-397-3) | 1998 | Jill D. Mellen · Michael Hutchins |
| Second Nature: Environmental Enrichment for Captive Animals | 978-1-56098-745-1 (1-56098-745-6) | 1998 | Jill D. Mellen · Michael Hutchins |