Klomp, H., & Teerink, B. J. 1973: The density of the invertebrate summer fauna on the crowns of pine trees, Pinus sylvestris in the central part of the Netherlands. - Beitr├Ąge Zur Entomologie = Contributions to Entomology 23(5-8): 325-340 - doi: 10.21248/contrib.entomol.23.5-8.325-340