@TechReport{economics.dp.2009-4,
 author = {Winkler, Ralph},
 title = {Now or Never: Environmental Protection under Hyperbolic Discounting},
 type = {Economics Discussion Paper},
 institution = {Kiel Institute for the World Economy},
 year = {2009},
 number = {2009-4},
 url = {http://www.economics-ejournal.org/economics/discussionpapers/2009-4}
}