Links to citations in Ethos lesson 3

[libcce]

@yochannah if you can track down the links for the citations in:
https://github.com/opensciency/sprint-content/blob/main/ethos-of-open/lesson3-open-stakeholders.md

[libcce]

Also for https://github.com/opensciency/sprint-content/blob/main/ethos-of-open/lesson4-impact-of-open.md