1887-1975 artenschutz bedrohtetiere bescherming biography biologen biologists biology business conservacion conservación conservation conservationofnaturalresources development earth ecologia ecologie ecologisme ecology ecología economics endangeredspecies environmentalconservation environmentalism environmentalprotection environmentalsciences environmentandecology environnement exploitatie filosofia filosofía geographie geography greatbritain histoire historia history huxley julian medioambiente milieubescherming milieugedrag nature natureconservation nonfiction philosophie philosophy philosophyofnature protecciondelmedioambiente proteccióndel protection recursosnaturales science sustainabledevelopment theorie umweltschutz unesco wildanimals wildlifeconservation wildlifeutilization wz100h986d1993 écologie écologisme