Encyclopedias, Almanacs, Transcripts, and Maps
- Recharge Zone
- Reclamation
- recombinant DNA research
- Reconstructionist Judaism
- Record of Decision
- Record-Setting Weather
- Recreation in and on Freshwaters
- Recreation in and on the Oceans
- Recreational Uses of Water
- rectangle
- Recyclables
- red admiral
- red blood cell
- redcurrant
- Redgrave, Sir Steven
- redshank
- Redwoods
- Reference Works
- Refineries
- Refining, History of