  We have computed $ B_K $ with staggered fermions, using two different
methods: both in the one spin trace form and two spin trace form. Renormalized
results in both forms are in good agreement. The numerical simulations were
performed on a $ 16^3 \times 40 $ lattice in full QCD with $ \beta = 5.7 $. We
also tried an improved wall source method in order to select only the
pseudo-Goldstone bosons and compare the numerical results obtained with those
from the conventional wall source method. We have studied $ B_K $ with a series
of non-degenerate quark anti-quark pairs and saw no effect on $ B_K $, although
dramatic effects in the chiral limit were seen on the individual terms making
up $ B_K $.
