- freely available
Sustainability 2012, 4(9), 2209-2209; doi:10.3390/su4092209
The authors wish to insert this additional sentence in the Acknowledgments section:
“The views expressed in this paper are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.”
© 2012 by the authors; licensee MDPI, Basel, Switzerland. This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).