− | Mathis Wackernagel, William E. Rees [http://www.sciencedirect.com/science/article/pii/S0921800996000778 Perceptual and structural barriers to investing in natural capital: Economics from an ecological footprint perspective], Ecological Economics, Volume 20, Issue 1, January 1997, Pages 3-24 | + | *Mathis Wackernagel, William E. Rees [http://www.sciencedirect.com/science/article/pii/S0921800996000778 Perceptual and structural barriers to investing in natural capital: Economics from an ecological footprint perspective], Ecological Economics, Volume 20, Issue 1, January 1997, Pages 3-24 |
| + | * AnnMari Jansson, [https://books.google.co.uk/books?hl=iw&lr=&id=yk8VDczLZj4C&oi=fnd&pg=PR2&dq=natural+capital&ots=FIOM3cqn5J&sig=uR9vNs0CppSkCLvukmOtEduhT20#v=onepage&q=natural%20capital&f=false Investing in Natural Cpital: The Ecological Economics Approach to Sustainability], Island Press, 1994 |