note from Journal website "All volumes: Issues older than five years are open access. Full-text available online starting from the first edition of 1950. Issues of last five years are free available only for print edition subscribers. Access online to these issues is regulated by Internet Protocol address. Subscribers should submit their IP addresses to the Rivista to ensure continued access. Must be a paid subscriber to each of the most recent five years to access the online issues." (http://rivista.math.unipr.it/vols.html). 31.3.2020--MMM.
HERDC documentation added to dark upload - HD 5/1/21