- 3 Dirac equation 1 Feynman proper time paradigm 1 Fock multitime approach 1 Fock space 1 Jordan–Wigner fermionization 1 Lagrangian formalism 1 Schr¨odinger–Foldy equation 1 bipartite entanglement 1 boson-fermion mixtures 1 charged particle inertial mass problem 1 charged particle self-interaction problem 1 composite bosons (cobosons, quasibosons) 1 composite fermions (cofermions) 1 dynamical mean field theory 1 entanglement entropy 1 fermionic doublet 1 fermionization 1 frustrated models 1 g-factor 1 g-фактор 1 least action principle 1 magnetocaloric effect 1 mean-field approximation 1 one-dimensional quantum spin models 1 pseudospin-electron model 1 purity 1 quantum Maxwell electrodynamics 1 quantum fermionic field 1 quantum phase transition 1