How to cite paper when there is a gap between conference date and publication date We are preparing conference proceedings of a research unit to be published online for the first time. Their first conference was in 2010. We are developing their website with export citation options for each paper. But due to the gap in time between conference date (e.g. 2010) and online publication date (2016) we are confused how to build the citation style basing on APA. Especially that they will publish those papers within proceedings of special issue in their proceedings website under ISSN and not ISBN which mean serial volumes each one designed for one conference proceedings.
so, what is the best format of such citations please?
What matters is the publication date, not the date of the conference. I don't know APA well enough, but in my field, the format would look like this:

Wolfgang Bangerth, "What is reality?", Proceedings of the 12th 
conference on impossible research, South Pole, March 12-24, 2010,
A. Stnas (ed.), Springer 2016.


In other words, the date of the conference appears as part of the "Proceedings of ..." text, whereas the date of publication (2016) is the normative date of publication.