TY - BOOK AU - Roelfsema, P. R. TI - Radio recombination line observations of HII regions and planetary nebulae PY - 1958/// CY - Groningen PB - Groningen University KW - Astronomy and Astrophysics Thesaurus KW - H II Regions KW - Ph.D.Thesis KW - Planetary Nebulae KW - Radio Recombination Lines ER -