Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates


    This is a preview of subscription content, log in to check access.

    Rights and permissions

    Reprints and Permissions

    About this article

    Cite this article

    Errata-corrige. Rend. Circ. Matem. Palermo 32, 402 (1911).

    Download citation