I've used the tool Publish or Perish to search through 1000 academic papers on Google Scholar with the term "Service Design" in their title. I've then listed these papers by their number of citations.

I've exported all my search results in a spreadsheet you can copy or explore if you want to go above the top 10 most cited Service Design academic papers.

I haven't sorted out all 980 academic papers manually so some papers might be about "ITIL Service Design" and not Service Design.