Еколошка храна — разлика између измена

* {{Cite book |ref= harv|author=Drinkwater, Laurie E.|chapter=Ecological Knowledge: Foundation for Sustainable Organic Agriculture|editor=Francis, Charles|title=Organic farming: the ecological system|publisher=ASA-CSSA-SSSA|year=2009|isbn=9780891181736|page=19|url=http://books.google.com/books?id=8HMfbQpNq60C&pg=PA19| ref = harv}}