McClure, M.S. 1977c Parasitism of the scale insect, Fiorinia externa (Homoptera: Diaspididae), by Aspidiotiphagus citrinus (Hymenoptera: Eulophidae) in a hemlock forest: density dependence.. Environmental Entomology 6: 551-555.

Notes: Study of the spatial distributions of F. externa and its parasite, A. citrinus, on Eastern hemlock, Tsuga canadensis.