The roots of polynomial $ p(z) $ are:
$$ \begin{aligned}z_1 &= 1.0523+0.5248i\\[1 em]z_2 &= 1.0523-0.5248i\\[1 em]z_3 &= -3.0523+2.269i\\[1 em]z_4 &= -3.0523-2.269i \end{aligned} $$Polynomial $ z^4+4z^3+3z^2-22z+20 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.