World health Organization. (2001). Health research methodology: A guide for training in research methodology (2nd- ed.). World Health organization.
Παραπομπή σε μορφή Chicago (17η εκδ.)World health Organization. Health Research Methodology: A Guide for Training in Research Methodology. 2nd- ed. Manila: World Health organization, 2001.
Παραπομπή σε μορφή MLA (8th εκδ.)World health Organization. Health Research Methodology: A Guide for Training in Research Methodology. 2nd- ed. World Health organization, 2001.
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