Find All Rational Zeros of the Polynomial $p ( x ) = 9 x ^ { 4 } + 30 x ^ { 3 } + 13 x ^ { 2 } - 20 x + 4$

Find all rational zeros of the polynomial $p ( x ) = 9 x ^ { 4 } + 30 x ^ { 3 } + 13 x ^ { 2 } - 20 x + 4$ .