APA引文

(2011). Keeping track of our changing environment from Rio to Rio + 20 (1992-2012). UNEP.

Chicago Edition Citation

Keeping 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.