Special issue: the biological sulfur cycle: environmental science and technology / ed.: P.N.L. Lens and L.W. Hulshoff PolProceedings of the 4th international symposium on [environmental] biotechnology : 106th event of the European Federation of Biotechnology : 10-12 April 2000, Noordwijkerhout, The Netherlands / ed.: Sybe Hartmans and Piet LensGeuremissies uit de veehouderij : overzichtsrapportage 1996-1999 / N.W.M. Ogink, P.N. Lens