http://pec.lib.wvu.edu/record/P169931930Computation of fertilizer mixtures from extra-high analysis fertilizers.Journal article reprint from: <em>Journal of the American Society of Agronomy,</em> v.22:no.8 (1930:Aug.). Deatrick, E. P. (Eugene Peyton), 1889-Fertilizers.Fertilizers--Analysis.14256