Comments on Levin et al. and Rosen and Kopel: internal and external validity issues.
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D035843:Biomedical Research / Q000592:standards*; D023381:Endpoint Determination; D006801:Humans; D008297:Male; D010378:Pedophilia / Q000628:therapy*; D010410:Penile Erection / Q000502:physiology / Q000523:psychology; D015203:Reproducibility of Results