Perhaps you should try some spelling variations:
collaborative series » collaborative services, collaborative studies, collaborative agencies
collaborative border » collaborative leader, collaborative model, collaborative courses
sweetland digital » stand digital
digital theorien » digital stories, digital rhetoric, digital terrain

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: sweetland digital theorien ((collaborative series) or (collaborative border))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: sweetland digital theorien ((collaborative series) OR (collaborative border)).
• Adding a wildcard symbol may retrieve word variants: sweetland digital theorien ((collaborative series) or (collaborative border))*.