How to add a user-friendly option to link to nodes from body text or text-field? I'm looking for an option or module that provides the possibility to link to other internal nodes avoiding the usage of full html in a text field. Users should be able to highlight a term and assign a link to it. It would be nice to have a kind of select-list containing the available nodes to link to.

I have done this before, but only for external links and with a minified editor. But i have no idea how to put a list of nodes there. Is there an alternative to achieve this?
Sounds like you're looking for the LinkIt module.


  Linkit provides an easy interface for internal and external linking.
  Linkit links to nodes, users, managed files, terms and have basic
  support for all entities by default, using an autocomplete field. In
  7.x-2.4 there is also support for fields (text, textarea, and link).


If you have pretty paths I'd also suggest combining it with Pathologic, that way your links will have their path aliases applied rather than their direct links (i.e. node/123 will become about-us)