Perhaps you should try some spelling variations:
sc instability » disc instability, 5 instability, 4 instability
10 instability » 17 instability, _ instability, 5 instability
7 instability » _ instability
1 instability » _ instability, 5 instability, 4 instability
2c lehrbuch » 2 lehrbuch, 1 lehrbuch, zu lehrbuch

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: %22str%c3%b6mungsmechanik %((((sc instability) OR (7 instability))) OR (((10 instability) OR (1 instability))))%c3%a4t %2c lehrbuch%22.
• Adding a wildcard symbol may retrieve word variants: %22str%c3%b6mungsmechanik %((((sc instability) or (7 instability))) or (((10 instability) or (1 instability))))%c3%a4t %2c lehrbuch%22*.