Valkama, E., Salo, T., Esala, M. and Turtola, E. 2013. Grain quality and N uptake of spring cereals as affected by nitrogen fertilization in northern conditions: a meta-analysis. Agricultural and Food Science. 22, 2 (Jun. 2013), 208–222. DOI:https://doi.org/10.23986/afsci.7448.