Schmithusen, Franz(Chair of Forest Policy and Economics, Department of Environmental Sciences, Eidgenoessische Technische Hochschule (ETH) Zurich, 2004)
Baland, Jean-Marie; Platteau, Jean-Philippe(Faculte des Sciences economiques et sociales, Facultes Universitaire Notre-Dame de la Paix, Namur, Belgium, 1994)