Q. Sometimes a journal is not published during its cover year, and sometimes there is a considerable gap between the cover date and the actual publication, and it is important to include both dates—the cover date so that the article can be found, and the publication date so that its up-to-dateness upon publication can be assessed. Should the date be given as 1989 [1992], or as 1992 [1989]?
A. Journal users typically are aware of the time lag, but if it’s important to note it, simply annotate the citation. The formulation you suggest might confuse the matter, since it is normally used in citations to indicate date of original publication and date of reprinting.