Issue #20 Jun 30, 1970 Issue #21 Issue #22 Oct 31, 1970 Issue #23 Dec 31, 1970 Issue #24 Feb 28, 1971 Issue #25 Apr 30, 1971 Issue #26 Jun 01, 1971 Issue #27 Aug 31, 1971 Issue #28 Oct 31, 1971 Issue #29 Dec 31, 1971 Issue #30 Feb 29, 1972 Issue #31 Apr 01, 1972 Issue #32 Jun 30, 1972 Issue #33 Aug 31, 1972 Issue #34 Oct 31, 1972 Issue #35 Dec 31, 1972 Issue #36 Jan 01, 1973 Issue #37 Mar 31, 1973 Issue #38 May 31, 1973 Issue #39 Jun 30, 1973