P. Peltonen-Sainio, P. Pirinen, M. Laapas, H. M. Mäkelä, H. Ojanen, and A. Venäläinen, “Spatial and temporal variation in weather events critical for boreal agriculture: III Frost and winter time fluctuation”, AFSci, vol. 25, no. 1, pp. 71–80, Mar. 2016.