Hard to find those as many pack assemblers do not want to, and have no reason to, share details of their assembly methods. I haven’t read these following papers in a while (just scanned some of the links I have) but they might be worth a look-through to see what they say.
A friend of mine, who works with cell manufacturers and pack assemblers, has told me that everyone says the same thing…they avoid the center of the negative terminal “just because”. Spot-welding to that place can never be a good thing, and could be a bad thing, so they just don’t do it. They have no need to, and no interest in, checking with the different cell manufacturers for the technical details.