@inproceedings{88aa43b063504d57885623f8cb590776,
title = "The {"}21{"} mu m and {"}30{"} mu m emission features in planetary nebulae with Wolf-Rayet central stars",
abstract = "We present mid infrared spectra of two planetary nebulae with H poor central stars that exhibit the {"}21{"} and {"}30{"} mum emission features. These features are found in carbon rich dust surroundings. The presence of these features shows that these sources have suffered an extended period of carbon rich mass loss before becoming H poor. We discuss the occurrence of both O-rich and C-rich dust in the sample of planetary nebulae observed with the Infrared Space Observatory.",
author = "S Hony and LBFM Waters and Tielens, \{A. G. G. M.\}",
year = "2003",
language = "English",
isbn = "1-58381-148-6",
series = "IAU SYMPOSIA",
publisher = "ASTRONOMICAL SOC PACIFIC",
pages = "299--300",
editor = "S Kwok and M Dopita and R Sutherland",
booktitle = "Planetary Nebulae",
note = "209th Symposium of the International-Astronomical-Union ; Conference date: 19-11-2001 Through 23-11-2001",
}