Pontecorvo, B. (1957). "Mesonium and anti-mesonium"(PDF). Journal of Experimental and Theoretical Physics. 6: 429–431. Archived from the original(PDF) on 29 November 2020. Retrieved 15 April 2016.
Pontecorvo, B. (1957). "Mesonium and anti-mesonium"(PDF). Journal of Experimental and Theoretical Physics. 6: 429–431. Archived from the original(PDF) on 29 November 2020. Retrieved 15 April 2016.