  Consider elliptic curves $ E:\ y^{2} = x^{3} + D^{3} $ defined over the
quadratic field $\ \Q(\sqrt{-3}) $. Hecke $ L-$series attached to $ E $ are
studied, formulae for their values at $ s=1, $ and bound of 3-adic valuations
of these values are given. These results are complementary to those in [Q] and
[QZ], and are consistent with the predictions of the conjecture of Birch and
Swinnerton-Dyer.
