I had the same questions myself. I tried to follow the citation on wikipedia, but that links to a newspaper article that doesn't seem to mention it at all.
Edit: on the other hand, the claim "meta-analysis by Rutgers researchers found that Permanent DST would eliminate 171 pedestrian fatalities (a 13% reduction) per year.", does actually link to a paper: https://www.sciencedirect.com/science/article/abs/pii/S00014...