Conservation laws for electron vortices in strong-field ionisationYuxin Kang, Emilio Pisanty, Marcelo Ciappina, Maciej Lewenstein, Carla Figueira de Morisson Faria and Andrew S. MaxwellEur. Phys. J. D, 75 7 (2021) 199DOI: https://doi.org/10.1140/epjd/s10053-021-00214-4