Perhaps you should try some spelling variations:
"viewed studium; grundkurs mathematik" » "viewed studium; vorkurs mathematik", "viewed studium; grundkurs informatik"
"reviewed studies; grundkurs mathematik" » "reviewed studies; vorkurs mathematik", "reviewed studies; grundkurs informatik", "review studies; grundkurs mathematik", "related studies; grundkurs mathematik", "repeated studies; grundkurs mathematik"
"resolved studies; grundkurs mathematik" » "resolved studies; vorkurs mathematik", "resolved studies; grundkurs informatik"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"vieweg studium; bruckenkurs mathematik\") OR (((((\"viewed studium; grundkurs mathematik\") OR (\"reviewed studies; grundkurs mathematik\"))) OR (\"resolved studies; grundkurs mathematik\"))))".
• Removing quotes may allow a broader search: (( vieweg studium; bruckenkurs mathematik ) OR ((((( viewed studium; grundkurs mathematik ) OR ( reviewed studies; grundkurs mathematik ))) OR ( resolved studies; grundkurs mathematik )))).
• Adding a wildcard symbol may retrieve word variants: (("vieweg studium; bruckenkurs mathematik") OR ((((("viewed studium; grundkurs mathematik") OR ("reviewed studies; grundkurs mathematik"))) OR ("resolved studies; grundkurs mathematik"))))*.