Virkajärvi, P., Huhta, H. and Tuuri, H. 1997. Effect of nitrogen fertilization, grass species and cultivar on sod production on Valkeasuo peat bog - a case study. Agricultural and Food Science. 6, 3 (Sep. 1997), 269–281. DOI:https://doi.org/10.23986/afsci.72790.