Astounding Science Fiction
Monthly from January 1930 with these exceptions:

1932: No issues in July, August, October, December
1933: No issues in February, April, May, June, July, August, September
1981: Two March issues: Mar 2 (asf-198103a.jpg) and Mar 30 (asf-198103b.jpg)
1982: Two March issues: Mar 1 (asf-198203a.jpg) and Mar 29 (asf-198203b.jpg)
      No April issue
      Two Sep issues Sep (asf-198209a.jpg) and Mid-Sep (asf-198209b.jpg)
1983: Two Sep issues Sep (asf-198309a.jpg) and Mid-Sep (asf-198309b.jpg)
1984: Two Dec issues Dec (asf-198412a.jpg) and Mid-Dec (asf-198412b.jpg)
1985: Two Dec issues Dec (asf-198512a.jpg) and Mid-Dec (asf-198512b.jpg)
1986: Two Dec issues Dec (asf-198612a.jpg) and Mid-Dec (asf-198612b.jpg)
1987: Two Dec issues Dec (asf-198712a.jpg) and Mid-Dec (asf-198712b.jpg)
1988: Two Dec issues Dec (asf-198812a.jpg) and Mid-Dec (asf-198812b.jpg)
1989: Two Dec issues Dec (asf-198912a.jpg) and Mid-Dec (asf-198912b.jpg)
1990: Two Dec issues Dec (asf-199012a.jpg) and Mid-Dec (asf-199012b.jpg)
1991: Two Dec issues Dec (asf-199112a.jpg) and Mid-Dec (asf-199112b.jpg)
1992: Two Dec issues Dec (asf-199212a.jpg) and Mid-Dec (asf-199212b.jpg)
1993: Two Dec issues Dec (asf-199312a.jpg) and Mid-Dec (asf-199312b.jpg)
1994: Two Dec issues Dec (asf-199412a.jpg) and Mid-Dec (asf-199412b.jpg)
1995: Two Dec issues Dec (asf-199512a.jpg) and Mid-Dec (asf-199512b.jpg)
1997: Jul/Aug combined (asf-199707.jpg)
1998: Jul/Aug combined (asf-199807.jpg)
1999: Jul/Aug combined (asf-199907.jpg)
2000: Jul/Aug combined (asf-200007.jpg)
2001: Jul/Aug combined (asf-200107.jpg)
2002: Jul/Aug combined (asf-200207.jpg)
2003: Jul/Aug combined (asf-200307.jpg)
2004: Jan/Feb combined (asf-200401.jpg) and Jul/Aug combined (asf-200407.jpg)
2005: Jan/Feb combined (asf-200501.jpg) and Jul/Aug combined (asf-200507.jpg)
2006: Jan/Feb combined (asf-200601.jpg) and Jul/Aug combined (asf-200607.jpg)