Publications go through different stages during their life-cycle.
Main milestone versions are:
The Versions Toolkit created by LSE recommends saving these milestone versions.
In most cases it is the Author's Accepted Manuscript (AAM) version that can be made available in City Research Online. It can also be called the 'Accepted version'.
If the research output is published using the Gold Open Access route, the published version can be used in City Research Online.
You can use SHERPA/RoMEO service to help you decide which version you are able to use in City Research Online.