Żuk, Piotr; Żuk, Paweł (24 September 2019). "One of the recent attacks of smallpox in Europe: A massive vaccination campaign during the epidemic in Wrocław in 1963". Vaccine. 37 (41): 6125—6131. doi:10.1016/j.vaccine.2019.08.038. PMID31455585. S2CID201654865.
Żuk, Piotr; Żuk, Paweł (24 September 2019). "One of the recent attacks of smallpox in Europe: A massive vaccination campaign during the epidemic in Wrocław in 1963". Vaccine. 37 (41): 6125—6131. doi:10.1016/j.vaccine.2019.08.038. PMID31455585. S2CID201654865.
Żuk, Piotr; Żuk, Paweł (24 September 2019). "One of the recent attacks of smallpox in Europe: A massive vaccination campaign during the epidemic in Wrocław in 1963". Vaccine. 37 (41): 6125—6131. doi:10.1016/j.vaccine.2019.08.038. PMID31455585. S2CID201654865.