Kalter S S, Heberling R L, Smith G C, Helmke R J
J Natl Cancer Inst. 1975 Sep;55(3):735-6. doi: 10.1093/jnci/55.3.735.
C-type virus particles were observed by electron microscopy in placentas from 7 of 9 chimpanzees (Pan sp.). These viruses were morphologically similar to those observed in placentas of other primates.