I have a question about the Dirac Equation. I know that if I have a given initial state in non-relativistic quantum mechanics, I can find the Fourier coefficients using that state, and then write down the wavefunction for any time. But if I have an initial state wavefunction (that is, the value of the wavefunction at t=0) in relativistic quantum mechanics, how do I find the wavefunction for any general time? Also, could anyone recommend books/websites that explain this in more detail? Thanks.