I am citing in Harvard style, so my entries end up something like this:
Widom, H. (1975). Asymptotic inversion of convolution operators, Publ. Math. Inst. Hautes Études Sci. 44: 191–240.
With the above entry, I noticed that the same author cited the year as 1975 from his later papers, but the publisher's website says volume 44 is from 1974. I looked at the actual journal volume and sure enough it has 1974 in big letters on the title page, but the small copyright notice says 1975. It seems that this is the journal volume for 1974, but was actually published in 1975. (According to the stamp on it, my university's library received its copy at the start of April 1975, so my speculation is that they only narrowly missed a deadline to pubish in 1974.)
My question is: how should I cite this? Should I mention both years? If so, how should I fit them in to the citation, and if not, which should I use?