Perhaps you should try some spelling variations:
disks instability » disk instability, disks stability, risk instability
disc instability » disk instability, disc stability, sc instability
10 instability » 1 instability, 17 instability, _ instability
2c instabilit » 20 instability, sc instability, 2.2 instability
4 instability » _ instability, 7 instability, 5 instability
2c lehrbuch » 2 lehrbuch, 1 lehrbuch, im 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 %((((2c instabilit) OR (((disc instability) OR (disks instability))))) OR (((10 instability) OR (4 instability))))%c3%a4t %2c lehrbuch%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22str%c3%b6mungsmechanik %((((2c instabilit) or (((disc instability) OR (disks instability))))) or (((10 instability) or (4 instability))))%c3%a4t %2c lehrbuch%22".
• Adding a wildcard symbol may retrieve word variants: %22str%c3%b6mungsmechanik %((((2c instabilit) or (((disc instability) OR (disks instability))))) or (((10 instability) or (4 instability))))%c3%a4t %2c lehrbuch%22*.