Developing a solid understanding of David Griffiths' Introduction to Elementary Particles
1.3 The antiparticle of the electron $e^-$ is the positron $e^+$.
Griffiths is famous for saying, "It can be shown that..." without showing it. The solutions manual often fills in these gaps. For instance, the derivation of the decay rate formula ( d\Gamma = \frac\mathcalM2m d\Pi_n ) is sketched in the text but fully worked out in the solutions to Problem 6.5.
The solutions manual for Griffiths' "Introduction to Elementary Particles" may be available:
