G.  Mathys and Guignard, E., ?Lessons learnt during nine years' work with Prospaltella pernciosi (Tow.), a parasite of the San José scale ( Quadraspidiotus pernciosus (Comst.))?, Entomophaga, vol. 12, pp. 212-222, 1967.

G.  Mathys and Guignard, E., ?Some aspects of the biological control of the San José scale ( Quadraspidiotus perniciosus Comst.) by means of the aphelinid Prospaltella pernciosi ?, Entomophaga, vol. 12, pp. 223-234, 1967.