Abundances of planetary nebulae NGC 2022, NGC 6818 and IC 4191

The ISO and IUE spectra of the elliptical nebulae NGC 2022, NGC 6818 and IC 4191 are presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to previous determinations. A discussion is also given of the exciting stars of the nebulae, and possible evolutionary effects.