[67] Zie bv. Ernst Young, 2002: Analysis of the Application of the Producer Pays Principle to Producers of Household Waste as a Driver Towards Sustainability, A Preliminary Discussion Document, Londen: Ernst Skumatz, Lisa A., 2002: Variable-rate of "Pay-as-you-throw" Waste Management: Answers to Frequently Asked Questions, Los Angeles: Reason Foundation.
[67] Voir par exemple Ernst Young, 2002: Analysis of the Application of the Producer Pays Principle to Producers of Household Waste as a Driver Towards Sustainability, A Preliminary Discussion Document, Londres: Ernst et Skumatz, Lisa A., 2002: Variable-rate or "Pay-as-you-throw" Waste Management: Answers to Frequently Asked Questions, Los Angeles: Reason Foundation.
