1. IPCC. Climate Change 2007: The Physical Science Basis. IPCC Secretariat, 2007
2. Wen Y P, Tang J, Shao Z Q, et al. A study of atmospheric CO2 concentration variations and emission from the soil surface at Mt. Waliguan (in Chinese). Q J Appli Meteorol, 1997, 8: 129–136
3. Wang M X, Liu W W, Rasmussen R A, et al. Long-term trend and seasonal cycle of atmospheric methane. Chin Sci Bull, 1990, 35: 213–216
4. Wang G C, Wen Y P, Kong Q X, et al. CO2 background concentration in the atmosphere over the Chinese mainland. Chin Sci Bull, 2002, 47: 1217–1220
5. Zhou L X, Zhou X J, Zhang X C, et al. Progress in the study of background greenhouse gases at Waliguan observatory (in Chinese). Acta Meteorol Sin, 2007, 65: 458–468