12-Oct-64, V.I. Arnold.
16-Nov-64, V.I. Arnold.
23-Nov-64, V.I. Arnold.
22-Nov-65, V.I. Arnold.
29-Nov-65, V.I. Arnold. (with comments by I.M.Gelfand)
6-Dec-65, V.I. Arnold.
13-Dec-65, V.I. Arnold.
5-Sep-66, V.I. Arnold.
10-Oct-66, V.I. Arnold.
21-Nov-66, V.I. Arnold.
28-Nov-66, V.I. Arnold.
6-Mar-67, V.I. Arnold.
22-Feb-71, V.I. Arnold.
1-Mar-71, V.I. Arnold.
15-Mar-71, V.I. Arnold.
29-Mar-71, V.I. Arnold.
15-Nov-71, V.I. Arnold.
19-Mar-73, V.I. Arnold.
7-Oct-74, V.I. Arnold.
13-Sep-76, V.I. Arnold.
30-Mar-81, V.I. Arnold.
22-Feb-82, V.I. Arnold.
22-Feb-82, V.I. Arnold.
21-Feb-83, V.I. Arnold.
12-Sep-83, V.I. Arnold.
3-Sep-84, V.I. Arnold.
9-Sep-85, V.I. Arnold.