I interpreted your 'any source' as in any individual paper, as normally people will mean 'individual studies' when they use the term 'source'. I apologize if that assumption was wrong.
The search query is indeed not helpful, which is why I stated that you should only use it if you really don't trust the generic reviews done. Hence I suggested to check the IPCC instead as a source, as this organisation reviews most research done in the area of climate change across the world.
A quick additional search (normal search engine) tells me that MIT just released such a review as well. The summary of this report states (page 16) that electric vehicles have on average 55% of the emissions compared to conventional vehicles, while hydrogen has 73% of the emissions compared to conventional vehicles.
Of course, we can check the source they have used in the full report and verify their conclusions against other reviews as well, just to be sure.
There are always specific situations where results differ, but we cannot make generic conclusions out of these results. That's why I always hate the 100% coal argument, as there are no regions (at least here in the EU) where this actually is the case. Also, the moment you ditch the coal makes the EVs suddenly much cleaner, while for conventional vehicles it is way harder to change their emission during their lifetime (This applies to hydrogen as well, assuming they're using electrolysed hydrogen).
