Planetary nebulae: advances in radio observations

Major advances are reviewed and include extensive continuum observations at 5 GHz of southern planetary nebulae; the highly successful aperture synthesis observations providing brightness temperature distributions with a resolution of a few arc seconds; the high sensitivity observations of radio recombination lines which have allowed the unambiguous detection of collisional broadening in NGC 7027; the very recent detection of molecular CO emission from NGC 7027, IC 418 and NGC 6543, and CO and OH emission from possible proto-planetary nebulae. (Auth.)