Paper delivered at the plenary session of the Eighth Congress on Low-Temperature Physics in Kiev, October 13, 1961.
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Оригинал: Пекар С И «Добавочные световые волны в кристаллах и экситонное поглощение» УФН 77 309–319 (1962); DOI: 10.3367/UFNr.0077.196206d.0309