Please refer to Section G3 in CTR 12th edition for instructions on how to cite conference information correctly. This includes:
It is quite common for individual conference papers to be published in the form of a journal article and instructions on how to cite this format can be found in the box below.
Either the URL or the DOI should only be included if the paper is only available online (as in the example below).
Ragazzi, M., Ghidini, F. (2017) ‘Environmental sustainability of universities: critical analysis of a green ranking’ (from the International conference on technologies and materials for renewable energy, environment and sustainability, TMREES17, Beirut Lebanon, 21-24 April 2017), Energy Procedia, 119 (July 2017), pp. 111-120. https://doi.org/10.1016/j.egypro.2017.07.054
Section G3.4 in CTR Harvard 12th edition.