Encyclopedias, Almanacs, Transcripts, and Maps
- Castrén, Matthias Alexander
- catalytic cracking
- Catherine of Siena
- cathode-ray oscilloscope
- Catholic Emancipation, Act of
- Cats (Felidae)
- Catskill Watershed Protection Plan
- Caudata (Salamanders and newts)
- Caves
- Cavies and Maras (Caviidae)
- CBI
- cell, electrolytic
- Celtic mythology
- Celtic Religion
- Celtic Religion: An Overview
- Celtic Religion: History of Study
- Center for Environmental Philosophy
- Center for Respect of Life and Environment
- Center for Rural Affairs
- Center for Science in the Public Interest