Sustainability Volume 13 Issue 4 Sustainability, Vol 13, Iss 2140, p 2140 (2021) Christensen, A A, Andersen, P S, Kjeldsen, C, Graversgaard, M, Andersen, E, Piil, K, Dalgaard, T, Olesen, J E & Vejre, H 2021, ' Achieving Sustainable Nitrogen Management in Mixed Farming Landscapes Based on Collaborative Planning ', Sustainability, bind 13, nr. 4, 2140 . https://doi.org/10.3390/su13042140 Christensen, A A, Andersen, P S, Kjeldsen, C, Graversgaard, M, Andersen, E, Piil, K, Dalgaard, T, Olesen, J E & Vejre, H 2021, ' Achieving sustainable nitrogen management in mixed farming landscapes based on collaborative planning ', Sustainability (Switzerland), vol. 13, no. 4, 2140, pp. 1-21 . https://doi.org/10.3390/su13042140