The Nature Index: a general framework for synthesizing knowledge on the state of biodiversity. oleh Grégoire Certain, Olav Skarpaas, Jarle-Werner Bjerke, Erik Framstad, Markus Lindholm, Jan-Erik Nilsen, Ann Norderhaug, Eivind Oug, Hans-Christian Pedersen, Ann-Kristin Schartau, Gro I van der Meeren, Iulie Aslaksen, Steinar Engen, Per-Arild Garnåsjordet, Pål Kvaløy, Magnar Lillegård, Nigel G Yoccoz, Signe Nybø