PE= PE, pulp × Egewogen referentie, pulp/(Egewogen referentie, pulp + Ereferentie, papier) + PE, papier × Ereferentie, papier/(Egewogen referentie, pulp + Ereferentie, papier).
PE= PE, pulp × Eweighted reference, pulp/(Eweighted reference, pulp + Ereference, paper) + PE, paper × Ereference, paper/(Eweighted reference, pulp + Ereference, paper)