title: Classification and nomenclature of viruses, 1973.
mesh_terms: D004267:DNA Viruses / Q000201:enzymology; D012321:DNA-Directed RNA Polymerases; D012328:RNA Viruses / Q000201:enzymology; D012194:RNA-Directed DNA Polymerase; D009626:Terminology as Topic; D014780:Viruses / Q000145:classification*
chemical_list: D012194:RNA-Directed DNA Polymerase; D012321:DNA-Directed RNA Polymerases