Koellner T, de Baan L, Beck T, Brandão M, Civit B, Goedkoop M, Margni M, Milà i Canals L, Müller-Wenk R, Weidema B P, Wittstock B – 2012 Principles for life cycle inventories of land use on a global scale. International Journal of Life Cycle Assessment 18 (6):1203-1215