| Authors | Year | |
|---|---|---|
| British Plant Communities | Rodwell, J.S. | 1991 |
| Mapping Critical Loads: A guidance to the criteria, calculations, data collection and mapping of critical loads. | H. Sverdup; W.… | 1990 |
| Critical loads for sulphur and nitrogen | J. Nilsson, P. Grennfelt | 1988 |