Informed consent.
D030881:Disclosure; D004992:Ethics, Medical; D006805:Human Experimentation; D007258:Informed Consent; D007603:Jurisprudence; D028681:Moral Obligations; D033281:Nontherapeutic Human Experimentation; D018570:Risk Assessment; D013587:Syphilis; D014481:United States; D014492:United States Public Health Service; D015004:Yellow Fever