I can’t understand how you’d need a citation for all of those. It seems some parts of your position rely on them happening, maybe on interpreting them differently, but are you really calling every single point there into question? I guess here’s a handful of sources slopped out about it.

https://www.hrw.org/report/2016/07/21/you-dont-exist/arbitrary-detentions-enforced-disappearances-and-torture-eastern https://www.crisisgroup.org/content/conflict-ukraines-donbas-visual-explainer https://www.state.gov/u-s-security-cooperation-with-ukraine