title: Positive prints of dense roentgenograms; a teaching aid.
mesh_terms: D001296:Audiovisual Aids; D003720:Densitometry; D010781:Photography; D011011:Pneumoencephalography; D011859:Radiography / Q000295:instrumentation*; D012796:Sialography; D013663:Teaching; D013679:Technology, Radiologic / Q000295:instrumentation*