John TJ, Samuel R (2000). „Herd immunity and herd effect: new insights and definitions”. Eur. J. Epidemiol.16 (7), 601–6. o. DOI:10.1023/A:1007626510002. PMID11078115.
John TJ, Samuel R (2000). „Herd immunity and herd effect: new insights and definitions”. Eur. J. Epidemiol.16 (7), 601–6. o. DOI:10.1023/A:1007626510002. PMID11078115.