1. N. A. Voronov, I. Y. Kobzarev, and N. B. Konyukhova, “Possibility of the existence of X mesons of a new type,” JETP Lett. 22, 290 (1975).
2. I. L. Bogolyubskii and V. G. Makhankov, “Lifetime of pulsating solitons in certain classical models,” JETP Lett. 24, 12–14 (1976).
3. I. L. Bogolyubskii and V. G. Makhankov, “Dynamics of spherically symmetrical pulsons of large amplitude,” JETP Lett. 25, 107–110 (1977).
4. M. Gleiser, “Pseudostable bubbles,” Phys. Rev. D 49, 2978 (1994).
5. E. J. Copeland, M. Gleiser, and H.-R. Müller, “Oscillons: Resonant configurations during bubble collapse,” Phys. Rev. D 52, 1920 (1995).