Soliton fermionic number from the heat kernel expansionA. Alonso-Izquierdo, Rodrigo Fresneda, J. Mateos Guilarte and D. VassilevichEur. Phys. J. C, 79 6 (2019) 525DOI: https://doi.org/10.1140/epjc/s10052-019-7041-8