Association of German Paper Mills eV: Paper ABC. Association of German Paper Mills eV, 2005.
↑ Recycle paper. (No longer available online.) Verband Deutscher Papierfabriken , 2007, p. 7 , archived from the original on December 17, 2013 ; accessed on December 17, 2013 : "Waste paper usage rate is the ratio of waste paper used to the amount of paper, cardboard and cardboard produced."