Perhaps you should try some spelling variations:
mathematical union » mathematical function, mathematical question, mathematical solution
ihrer grenzgebiete » ihre grenzgebiete, ihren grenzgebieten, der grenzgebiete
mathematical und » mathematica und, mathematical using, mathematical user
ergebnisse her » ergebnisse h, ergebnisse haben, ergebnisse host
models survey » modeling survey, models supply
model survey » model surgery, modern survey, moral 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 her ((mathematical und) OR (mathematical union)) ihrer grenzgebiete. 2. folge, a series of ((model survey) OR (models survey)) in mathematics.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ergebnisse her ((mathematical und) OR (mathematical union)) ihrer grenzgebiete. 2. folge, a series of ((model survey) or (models survey)) in mathematics".
• Adding a wildcard symbol may retrieve word variants: ergebnisse her ((mathematical und) OR (mathematical union)) ihrer grenzgebiete. 2. folge, a series of ((model survey) or (models survey)) in mathematics*.