Harries, F. H. and Burts, E. (1959). Laboratory studies of pear psyllas resistant to dieldrin and some related compounds. J. Econ. Entomol., 52, 530.
Harries, F. H. and Burts, E. C. (1965). Insecticide resistance in the pear psylla (P. pyricola Forster.). J. Econ. Entomol., 58, 172-73.
no entry in FAO bibliography.
Burts, E. C. (1974). Communication to FAO.
Croft, B. A., Burts, E. C., van de Baan, H. E., Westigard, P. H., and Riedl, H. (1989). Local and regional resistance to fenvalerate in Psylla pyricola Roerster (Homoptera: Psyllidae) in western North America. Can. Entomol., 121, 122-129.
Davis, D.W. (1984). Personal communication.
. (1967). Report of the First Session of the FAO Working Party of Experts on Resistance of Pests to Pesticides. FAO, Rome 1965.
Follett, P. A., Croft, B. A. and Westigard, P. H. (1985). Regional resistance to insecticides in Psylla pyricola from pear orchards in Oregon. Can. Entomol., 117, 565-573.
Howitt, A.J. (1974). Communication to FAO.
Jensen, G.L. (1974). Communication to FAO.
Kain, W.M. (1981). Personal communication.
Martelli, M. (1968). In: FAO 1969.
McMullen, R.C. (1965). In: FAO 1967.
Plaut, H.N. (1965). In: FAO 1967.
Riedl, H., Westigard, P. H., Bethell, R. S. and Detar, J. E. (1981). Problems with chemical control of pear psylla. Calif. Agric., 35, 7-9.
Simpson, C.M. (1965). In: FAO 1967.
Staubli, A. 1984. Communication to FAO.
Westigard, P. H. and Zwick, R. W. (1972). The pear psylla in Oregon. Oreg. State Univ. Agric. Stn. Tech. Bull., 122, 22 pp.