Perhaps you should try some spelling variations:
ihren grenzgebieten » ihre grenzgebiete
modern surveys » oder surveys, modern purveyors, modern surgery
modern survey » modern surgery, models survey, model survey
2c a » 12c a, 20 a, 21 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 mathematik und ((ihren grenzgebieten) OR (im grenzgebiet)). 2. folge%((((2c a) OR (c a))) OR (2 a)) series of ((modern surveys) OR (modern survey)) in mathematics%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%ergebnisse der mathematik und ((ihren grenzgebieten) or (im grenzgebiet)). 2. folge%((((2c a) or (c a))) or (2 a)) series of ((modern surveys) OR (modern survey)) in mathematics%22".
• Adding a wildcard symbol may retrieve word variants: %ergebnisse der mathematik und ((ihren grenzgebieten) or (im grenzgebiet)). 2. folge%((((2c a) or (c a))) or (2 a)) series of ((modern surveys) OR (modern survey)) in mathematics%22*.