Crosson E R. A cavity ring-down analyzer for measuring atmospheric levels of methane, carbon dioxide, and water vapor [J]. Applied Physics B, 2008, 92(3):403-408
Zhou L X, Conway T J, White J W C, et al. Long-term record of atmospheric CO2 and stable isotopic ratios at Waliguan Observatory:Background features and possible drivers, 1991-2002[J]. Global Biogeochemical Cycles, 2005, 19, GB3021 1-9, dio:10.1029/2004GB002430
Tsutsumi Y, Mori K, Ikegami M, et al. Long-term trends of greenhouse gases in regional and background events observed during 1998-2004 at Yonagunijima located to the east of the Asian continent [J]. Atmospheric Environment, 2006,40:5868-5879