C. A. M. Campbell. 1985. 7. Implications for Biological Control on Intensively Grown Outdoor Crops. 7.2. Hops (Humulus lupulus L.). Pages 192-194. In: N. W. Hussey, N. Scopes (editors). Biological Pest Control: The Glasshouse Experience, Ithaca, New York: Cornell University Press, 240 pages.
