I need to to reference the report [What leads developers towards the choice of a JavaScript framework?][1]. 

The authors are 

 - A. Pano, Free University of Bozen-Bolzano 
 - D. Graziotin, University of Stuttgart
 - P. Abrahamsson, Norwegian University of Science and Technology

I'm not sure how I would reference this using Vancouver notation, since the authors are from different universities?

Is somethings like this correct?

> A. Pano, D. Graziotin, P. Abrahamsson, “What leads developers towards the choice of a JavaScript framework?”, Free University of Bozen-Bolzano / University of Stuttgart / Norwegian University of Science and Technology, 2016, 49 pages.

Also, the guide from my university mentions that there should be a "report number" (report code?) in the reference for reports from universities, but I can't find any such number in the referenced report. What is this number, and is it mandatory?


  [1]: https://www.researchgate.net/publication/303221742_What_leads_developers_towards_the_choice_of_a_JavaScript_framework