Fermion family recurrences in the Dyson–Schwinger formalismFelipe J. Llanes-Estrada, Tim Van Cauteren and Ángel P. MartínEur. Phys. J. C, 51 4 (2007) 945-952DOI: https://doi.org/10.1140/epjc/s10052-007-0349-9