1. Alstrup, V. and Hansen, E. S.: 1977, Oikos 29, 290.
2. Asta, J. and Garrec, J. P.: 1980, Cryptogamie, Bryol. Lichenol. 1, 3.
3. Beckett, R. P. and Brown, D. H.: 1983a, Ann. Bot. 52, 43.
4. Beckett, R. P. and Brown, D. H.: 1983b, Cellular Uptake of Heavy Metals by Bryophytes and Lichens, ? 4th Intern. Conf. Heavy Metals Environ., Proceedings, pp. 447?450.
5. Beckett, R. P. and Brown, D. H.: 1984a, New Phytol. 97, 301.