1. S. Weinberg, The U(1) problem, Phys. Rev. D 11 (1975) 3583 [
INSPIRE
].
2. S.L. Adler, Axial vector vertex in spinor electrodynamics, Phys. Rev. 177 (1969) 2426 [
INSPIRE
].
3. J.S. Bell and R. Jackiw, A PCAC puzzle: 𝜋0→ γγ in the 𝜎 model, Nuovo Cim. A 60 (1969) 47 [
INSPIRE
].
4. G. 't Hooft , Symmetry breaking through Bell-lackiw anomalies, Phys. Rev. Lett. 37 (1976) 8 [
INSPIRE
].
5. G. 't Hooft, Computation of the quantum effects due to a four-dimensional pseudoparticle, Phys. Rev. D 14 (1976) 3432 [Erratum ibid. 18 (1978) 2199] [
INSPIRE
].