I wantlook for a reference of the following implication
Let $ X $ be a compact complex manifold,
If : 1) $ \chi (O_X) \neq0 $
2) the Universal covering does not contain compact subvariety
So $ K_X $ is big .
We know that $ K_X $ is big $\implies$ $ K_X $ is nef, when can we have the equivalent?