The text is a note at the end of a book, so there's not much of a context, I think:
«6.- Contemporary elite networks and "core-sets" in science are discussed in...»
Those Contemporary elite networks and "core-sets" in science are groups of prominent scientists that played the role of spreading the theories they liked.
I know that, in the end, this is not much more than what I first posted, but it is a note, not a full text, and that is all the context the author provides the reader with. Because of this, I also thought "core-set" should be something common. Now I see it is not.