P-ISSN 0008-0845
E-ISSN 2160-8091
Vol. 17, Issue 1, 1963January 01, 1963 PDT 
ccby-nc-nd-4.0 
Pear psylla: In abandoned orchards 
Pear psylla: In abandoned orchards
P Westigard, H Madsen, 
Westigard, P, and H Madsen. 1963. “Pear Psylla: In Abandoned Orchards.” California Agriculture 17 (1): 6–9.