This
https://phas.ubc.ca/~mcmillan/overview.htmlAnd pedagogical books like student friendly quantum field theory
A lot of QFT books will out of the blue talk about fields, as if you are supposed to know what they are. Heres the interesting part: QFT is just like normal quantum mechanics, there are wavefunctions that live on a Hilbert space, clearly defined operators with a defined action on wavefunctions, hermitian operators that are observables, wavefunction evolution given by a hamiltonian.
Somehow people prefer to talk about fields, but they have the same information codified within, might be easier to do calculations in such formalism.
