Life sciences and space research XXIV(4) : natural and artificial ecosystems : proceedings of the Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F (Meetings F10, F11, F1 and F12) of the COSPAR Twenty-eighth Plenary Meeting held in The Hague, The Netherlands, 25 June-6 July 1990 / edited by R.D. MacElroy ... [et al.]