A. Potekhin. (2011)cite arxiv:1102.5735 Comment: 28 pages, 8 figures (in v2 and v3, several typos have been fixed). Invited topical review for the special issue of Uspekhi Fiz. Nauk (Physics - Uspekhi) in memory of V. L. Ginzburg (translated from Russian by Yu. V. Morozov, edited by A. M. Semikhatov and by the author).