Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) László Sarkadi and Tom Kirchner and A Igarashi and László Gulyás,Two-electron cusp in the double ionization of helium,Physical Review A,1050-2947,American Physical Society (APS),2010-09-10,82,,,https://cir.nii.ac.jp/crid/1871428067831520384,https://doi.org/10.1103/physreva.82.032705