How to access data in front matter of other contents?

I’m writing a website for our research lab. The content types are people, projects, and publications. In the front matter of a project, there is a parameter members to describe people involved. And for a publication, there is a parameter authors. How can these parameters be accessed when rendering a person (i.e., the metadata of some content when rendering other content)? I found taxonomies inappropriate here, since projects and publications are contents themselves.

It seems that I can iterate over .Site.Pages to get the required content, and use where to filter for specific type, right?

That’s true, that’s done like this:

{{ range where .Data.Pages "Section" "post" }}
   {{ .Content }}
{{ end }}

Also see template functions in Hugo.