I'm looking for an introductory text on Dirichlet characters and the L-series of a field K, specifically for quartic extensions of $\mathbb{Q}$. I have Davenport's Multiplicative Number Theory, Ireland/Rosen, Marcus' Number Fields, and Washington's Cyclotomic Fields, but things seem to be scattered and I was hoping for more concrete examples. Does anyone have any suggestions? This graduate student would appreciate any ideas you have!

Thanks!