Soliton fermionic number from the heat kernel expansion A. Alonso-Izquierdo, Rodrigo Fresneda, J. Mateos Guilarte and D. Vassilevich Eur. Phys. J. C, 79 6 (2019) 525 Published online: 20 June 2019 DOI: 10.1140/epjc/s10052-019-7041-8