Perhaps you should try some spelling variations:
ihren grenzgebieten » ihre grenzgebiete
mathematical using » mathematica using, mathematics using, mathematical testing
mathematical union » mathematical function, mathematical question, mathematical solution
ihrer grenzgebiete » ihre grenzgebiete, der grenzgebiete, deren grenzgebiete
mathematical und » mathematica und, mathematical user, mathematical path
modern surgery » open surgery, modern slavery
modern survey » models survey, model survey, modeling survey

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ergebnisse der ((((mathematical und) OR (mathematical using))) OR (mathematical union)) ((ihrer grenzgebiete) OR (ihren grenzgebieten)). 2. folge, a series of ((modern survey) OR (modern surgery)) in mathematics.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ergebnisse der ((((mathematical und) or (mathematical using))) or (mathematical union)) ((ihrer grenzgebiete) or (ihren grenzgebieten)). 2. folge, a series of ((modern survey) OR (modern surgery)) in mathematics".
• Adding a wildcard symbol may retrieve word variants: ergebnisse der ((((mathematical und) or (mathematical using))) or (mathematical union)) ((ihrer grenzgebiete) or (ihren grenzgebieten)). 2. folge, a series of ((modern survey) OR (modern surgery)) in mathematics*.