Encyclopedias, Almanacs, Transcripts, and Maps
- Radioactive Tracers
- Radioactive Tracers
- Radioactivity, Discovery of
- Radioisotopes and Their Uses in Microbiology and Immunology
- Radioisotopes in Medicine
- Radioisotopes in Medicine
- Radiological Threat Analysis
- Radionic Association
- Radon Production, Detection, and Elimination
- Raelian Movement
- Rafaello Bombelli
- Raffé, W(alter) G(eorge) (1888-ca. 1950)
- Ragfish: Icosteoidei
- Ragnar Arthur Granit
- Ragnar Lothbrok
- Rahu
- Rails
- Rails
- Rails, Coots, and Moorhens: Rallidae
- Rainbowfishes and Silversides: Atheriniformes