Vol. no. and date for v. 21, no. 1- correspond to no. of years of publication and date of coverage of the original Russian journal. The Russian journal dropped no. of years of publication with 1977, resulting in a discrepancy in numbering between this translation journal and the Russian original; e.g., v. 37 (1982) corresponds to v. 23 (1982) of the original. Date of coverage corresponds to that of the Russian original