أنظر: E.W.Perdijk, J. Luijten and A.J.Selderijk, An Eco Label for Footwear - Draft of a study, January 1994, p.19.
См. E.W. Perdijk, J. Luijten and A.J. Selderijk, An Eco-Label for Footwear - Draft of a Study, January 1994, p. 19.