Cardinal electors for the 1958 conclave
The papal conclave of 1958 was convened to elect a pope, the leader of the Catholic Church, to succeed Pope Pius XII following his death on 9 October 1958. Of the 54 members of the College of Cardinals at the time of Pius XII's death, 51 participated in the subsequent conclave.
Source: Wikipedia — Cardinal electors for the 1958 conclave (CC BY-SA 4.0)