@article{article4f0e9dd1,
title   = {Abundances of southern type I planetary nebulae},
author = {Freitas Pacheco, José Antonio and Maciel, Walter Junqueira and Costa, Roberto Dell'Aglio Dias da and Barbuy, Beatriz Leonor Silveira},
year = {1991},
journal   = {Astronomy and Astrophysics}
}