Russell, K., Hamm, P., Sutherland, J., Hansen, E., Littke, W., Kliejunas, J., Kanaskie, A., James, R., Campbell, S., Overhulser, D., Schowalter, T., Capizzi, J., McElroy, F., Hermann, R., Landis, T., & Steinfeld, D. (1990). Growing healthy seedlings : identification and management of pests in Northwest forest nurseries.