Hamm PB, Hansen EM. Identification of Phytophthora spp. known to attack conifers in the Pacific Northwest. Northwest Sci. 1987  ;61:103-109.

Hamm PB, Hansen EM. Pathogenicity of Phytophthora species to Pacific Northwest conifers. European Journal of Forest Pathology [Internet]. 1982  ;12:167?174. Available from: http://dx.doi.org/10.1111/j.1439-0329.1982.tb01390.x

Hamm PB, Hansen EM. Phytophthora pseudotsugae, a new species causing root rot of Douglas-fir. Can. J. Bot. [Internet]. 1983  ;61:2626?2631. Available from: http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=eng&journal=cjb&volume=61&year=1983&issue=10&msno=b83-289

Hamm PB, Hansen EM. Improved method for isolating Phytophthora lateralis from soil. Plant disease. 1984  ;68:517-519.