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Hansen EM, Maxwell DP. Species of the Phytophthora megasperma complex. Mycologia, [Internet]. 1991  ;83:376-381. Available from: http://www.jstor.org/stable/3759999

Hansen EM, Roth LF, Hamm PB, Julis. AJ. Survival, spread, and pathogenicity of Phytophthora spp. on Douglas-fir seedlings planted on forest sites. Phytopathology 70: [Internet]. 1980  ;70:422-425. Available from: http://www.apsnet.org/publications/phytopathology/backissues/Documents/1980Abstracts/Phyto70_422.htm

Hansen EM, Parke JL, Sutton W. Susceptibility of Oregon forest trees and shrubs to Phytophthora ramorum: a comparison of artificial inoculation and natural infection. Plant Disease [Internet]. 2005  ;89:63-70. Available from: http://apsjournals.apsnet.org/doi/abs/10.1094/PD-89-0063