1957 January-February March-April May-June July-August (September-October) November-December
The Sept-Oct 1956 issue is Vol. 28 #2; the Jan-Feb 1957 issue is Vol. 28 #3. The webmaster can find no public acknowledgement for the omission of Nov-Dec 1956 issue.
The parenthesis around the 1957 September-October issue is webmaster’s acknowledgement that he does not have a copy of that magazine issue.