Yung, et.al., on: O isotopic composition of CO2 ...

Mao-Chang Liang, Geoffrey A. Blake, Brenton R. Lewis and Yuk L. Yung. (2007) Oxygen isotopic composition of carbon dioxide in the middle atmosphere. Proceedings of the National Academy of Sciences of the United States of America, 104(1):21-25, 2 January 2007. CaltechAUTHORS.

Freely available online through the PNAS open access option.