  Measuring the oscillation frequency in the $B_s^0$-meson system was one of
the main goals in b-physics for the two experiments CDF and D{\O} at the
Tevatron-Collider since the start of RunII in the year 2001. The D{\O}
collaboration was the first experiment, which was able to give a two sided
limit for the oscillation frequency of $B_s^0$ mesons. Shortly after the CDF
collaboration confirmed this result and was able to give a $5\sigma$
measurement.
