  We report the first observation of magnetic Feshbach resonances between
${}^{173}$Yb and $^{133}$Cs. In a mixture of Cs atoms prepared in the $(f=3,
m_f=3)$ state and unpolarized fermionic ${}^{173}$Yb we observe resonant atom
loss due to two sets of magnetic Feshbach resonances around 622~G and 702~G.
Resonances for individual Yb nuclear spin components $m_{i,\mathrm{Yb}}$ are
split by its interaction with the Cs electronic spin, which also provides the
main coupling mechanism for the observed resonances. The observed splittings
and relative resonance strengths are in good agreement with theoretical
predictions from coupled-channel calculations.
