SAARELA, I., A. JÄRVI, and H. HAKKOLA. “Phosphorus Status of Diverse Soils in Finland As Influenced by Long-Term P Fertilisation I.Native and Previously Applied P at 24 Experimental Sites”. Agricultural and Food Science, vol. 12, no. 2, Jan. 2003, pp. 117-32, doi:10.23986/afsci.5747.