1. United Nations Environmental Program: Ozone Secretariat. In The Montreal Protocol on Substances that Deplete the Ozone Layer: as either adjusted and/or amended in London 1990, Copenhagen 1992, Vienna 1995, Montreal 1997, Beijing 1999; 2000
2. Ravishankara AR, Daniel JS, Portmann RW (2009) Science 326:123–125
3. United States Environmental Protection Agency. ‘2010 US Greenhouse Gas Inventory Report: Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990–2008′. 2010, U.S. EPA # 430-R-10-006
4. Leuenberger M, Siegenthaler U (1992) Nature 360:451
5. MacFarling Meure C, Etheridge D, Trudinger C, Steele P, Langenfelds R, van Ommen T, Smith A, Elkins J (2006) Geophys Res Lett 33:L14810