THE STRUCTURAL FEATURES OF THE PLANETARY NEBULAE Open PDF Document Details Document Type Technical Report Publication Date Jul 17, 1954 Accession Number AD0047171 Entities People Lawrence H. Aller Organizations Michigan State University Tags Communities of Interest Air Platforms Energy and Power Technologies DTIC Thesaurus Topics Brightness Calibration Cameras Distortion Emission Spectra Emulsions Government Procurement Governments Observation Observatories Observers Photographic Emulsions Photographs Photography Radial Velocity Spectra Spectral Lines