Isotopic ratios in Titan's atmosphere from Cassini CIRS limb sounding: CO2 at low and midlatitudes - Nixon, C; Jennings, D; Bezard, B; Teanby, N; Achterberg, R; Coustenis, A; Vinatier, S; Irwin, P; Romani, P; Hewagama, T; Flasar, F (2008)