PN-Carbon Yields and the Chemical Evolution of the Galactic Disk
  Two sets of observational carbon stellar yields for low-and-intermediate mass stars are computed based on planetary nebula abundances derived from C II lambda 4267 and C III lambda lambda 1906 + 1909 lines, respectively. These observational yields are assumed in chemical evolution models for the solar vicinity and the Galactic disk. C/O values observed in stars of the solar vicinity and Galactic H II regions are compared with those predicted by chemical evolution models for the Galaxy. I conclude that the C yields derived from permitted lines are in better agreement with the observational constraints than those derived from forbidden lines. 
Leticia Carigi