Perhaps you should try some spelling variations:
ihren grenzgebieten » ihre grenzgebiete
ihrer grenzgebiete » ihre grenzgebiete, der grenzgebiete, deren grenzgebiete
mathematical union » mathematical function, mathematical question, mathematical solution
modern purveyors » modern survey, modern purgatory, power purveyor
mathematical und » mathematica und, mathematical using, mathematical user
12c a » 12c _
2c a » 2 a, c a, 20 a

Try widening your search to All Fields.

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)) ((ihrer grenzgebiete) OR (ihren grenzgebieten)). 2. folge%((2c a) OR (12c a)) series of modern purveyors in mathematics%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%ergebnisse der ((mathematical und) OR (mathematical union)) ((ihrer grenzgebiete) or (ihren grenzgebieten)). 2. folge%((2c a) or (12c a)) series of modern purveyors in mathematics%22".
• Adding a wildcard symbol may retrieve word variants: %ergebnisse der ((mathematical und) OR (mathematical union)) ((ihrer grenzgebiete) or (ihren grenzgebieten)). 2. folge%((2c a) or (12c a)) series of modern purveyors in mathematics%22*.