Reviews of topical problems

A.B. Migdal “Vacuum polarization in strong fields and pion condensation” Sov. Phys. Usp. 20 879–898 (1977)

S.A. Akhmanov, N.I. Koroteev “Spectroscopy of light scattering and nonlinear optics. Nonlinear-optical methods of active spectroscopy of Raman and Rayleigh scattering” Sov. Phys. Usp. 20 899–936 (1977)

Yu.V. Petrov “The Oklo natural nuclear reactor” Sov. Phys. Usp. 20 937–944 (1977)

Ya.B. Zel’dovich “Gravitation, charges, cosmology, and coherence” Sov. Phys. Usp. 20 945–955 (1977)

Physics of our days

B.A. Arbuzov, A.A. Logunov “Structure of elementary particles and relationships between the different forces of nature” Sov. Phys. Usp. 20 956–969 (1977)

From the history of physics

S.N. Vernov, N.A. Dobrotin “Fiftieth anniversary of a fundamental discovery in cosmicray physics” Sov. Phys. Usp. 20 970–972 (1977)