1991 journal article
Effects of plant debris on intensity of leaf spot diseases, incidence of pathogens, and growth of alfalfa
Phytopathology, 81(5), 511.
By: J. Duthie & C. Campbell
Efficiency of multistage sampling for estimation of intensity of leaf spot disease of alfalfa in field experiments
Phytopathology, 81(9), 959.
By: J. Duthie, C. Campbell & L. Nelson