<ref>John Seale, "Origins of the AIDS Viruses, HIV-1 and HIV-2: Fact or Fiction?", The British Journal of the Royal Society of Medicine, 1988 (81: 617-619).</ref> | <ref>John Seale, "Origins of the AIDS Viruses, HIV-1 and HIV-2: Fact or Fiction?", The British Journal of the Royal Society of Medicine, 1988 (81: 617-619).</ref> |