A good reference is Appendix B, titled "The role of Mileva Einstein" in the excellent book "Who cares about Particle Physics?" by Pauline Gagnon (particle physicist at CERN/ATLAS). Here is a 4-page version, "The Forgotten Life of Mileva Marić Einstein" also by Pauline Gagnon:
I read the appendix by chance when I read the book itself, and I have to say it's fascinating. The book is about particle physics at CERN in general, and there's a late chapter about diversity at CERN, to which this is an appendix. The whole book is great, I read it as a refresher, as I left the field of (particle) physics many years ago. Based on the evidence presented, it is possible that some (how much?) of Einstein's most famous work was a collaboration between Maric and Einstein, and they simply didn't include her in the credits, because it was easier to get published as a single male author (and they needed the money).
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