Encyclopedias, Almanacs, Transcripts, and Maps
- Spectral Classification of Stars
- Spectral Classification of Stars
- Spectral Flames
- Spectral Lines
- Spectral Lines
- Spectrum—Society for Psychical and Spiritual Studies
- Specularii
- Speech Synthesizer
- Spelaeogriphaceans: Spelaeogriphacea
- Spence, (James) Lewis (Thomas Chalmers) (1874-1955)
- Spencer Fullerton Baird
- Spencer, Herbert
- Sperm Whales: Physeteridae
- Spheres
- Spherocytosis, hereditary
- Spiders, Scorpions, Mites, and Ticks: Arachnida
- Spiderwort Family
- Spiderwort Family
- Spiegelschrift
- Spin of Subatomic Particles