(2011). Keeping track of our changing environment from Rio to Rio + 20 (1992-2012). UNEP.
Chicago Edition CitationKeeping Track of Our Changing Environment from Rio to Rio + 20 (1992-2012). Nairobi: UNEP, 2011.
MLA引文Keeping Track of Our Changing Environment from Rio to Rio + 20 (1992-2012). UNEP, 2011.
警告:这些引文格式不一定是100%准确.