Subject
- Forests and forestry -- Research -- Belgium1
- Forests and forestry -- Research -- Czechoslovakia1
- Forests and forestry -- Research -- International cooperation1
- Forests and forestry -- Research -- Netherlands1
- Forests and forestry -- Research -- Poland1
- Forests and forestry -- Research -- Yugoslavia1
- International Biological Programme -- Research -- Belgium1
- International Biological Programme -- Research -- Czechoslovakia[remove]1
- International Biological Programme -- Research -- Netherlands1
- International Biological Programme -- Research -- Poland1
- International Biological Programme -- Research -- Yugoslavia1
- U.S. International Biological Program. Coniferous Forest Biome1