Finding roots of sextic in radicals



If my calculations are correct, the roots of x^6 + 3*x^5 + 6*x^4 +
3*x^3 + 9*x +9 should all be expressible by radicals. In fact, they
are all polynomials in terms of 2^(1/3) and a cube root of unity.

How can I make Maxima tell me what the roots actually are?

- Jordi G. H.