Expanded text of a paper delivered on 28 September 1967 at the Session of the Division of General and Applied Physics of the USSR Academy of Sciences.
Оригинал: Алексеевский Н Е «Новые сверхпроводники» УФН 95 253–266 (1968); DOI: 10.3367/UFNr.0095.196806a.0253