Salk, J. (1977). Polio vaccines and polioviruses.
Chicago Style aipamenaSalk, J. Polio Vaccines and Polioviruses. 1977.
MLA aipamenaSalk, J. Polio Vaccines and Polioviruses. 1977.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.
APA aipamena