Encyclopedias, Almanacs, Transcripts, and Maps
- reflex action
- reflexor
- Reformation
- Refrigerators and Freezers
- Refuse-Derived Fuels
- Regan, Tom [Thomas Howard] (1938 – ) American Philosopher and Animal Rights Activist
- Regulation and Rates for Electricity
- Regulatory Review
- Reguly, Antal
- Reilly, William Kane (1940 – ) American Conservationist and Environmental Protection Agency Administrator
- Reimarus, Hermann Samuel
- Reinach, Salomon
- Reines, Yits?aq Ya?aqov
- Reiy?kai Ky?dan
- relative density
- Relics
- Relict Species
- Religion and the Environment
- Religionsgeschichtliche Schule
- Religious Broadcasting