Perhaps you should try some spelling variations:
mathematical union » mathematical function, mathematical question, mathematical solution
ihre grenzgebiete » ihren grenzgebieten, die grenzgebiete, im grenzgebiet
mathematical und » mathematica und, mathematical using, mathematical user
der grenzgebiete » die grenzgebiete, dem grenzgebiet, und grenzgebiete
modern surveys » modern survey, oder surveys, modern purveyors

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 union)) ((der grenzgebiete) OR (ihre grenzgebiete)). 2. folge, a series of modern surveys in mathematics.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ergebnisse der ((mathematical und) OR (mathematical union)) ((der grenzgebiete) or (ihre grenzgebiete)). 2. folge, a series of modern surveys in mathematics".
• Adding a wildcard symbol may retrieve word variants: ergebnisse der ((mathematical und) OR (mathematical union)) ((der grenzgebiete) or (ihre grenzgebiete)). 2. folge, a series of modern surveys in mathematics*.