Abrahamson, L. P., H.-M. Chu, and D. M. Norris. 1967. Symbiotic interrelationships between microbes and ambrosia beetles: II, The organs of microbial transport and perpetuation in Trypodendron betulae and Trypodendron retusum (Coleoptera: Scolytidae) . Entomological Society of America, Annals 60:1107-1110.