According to website
the young Italian rider Emilio Soprani lost his life at the age of 22, on the Circuito della Superba in Genoa, on 05 May 1947, while making his debut on a Gilera 4 cylinder bike.
I am sure that the source is wrong. Searching in contemporary Italian newspapers on-line (La Stampa, Corriere dello Sport) no news about his fatal accident at Genoa in 1947 is available. Indeed, he was reported to be still active in the World Motorcycle Championship in 1950 riding a Moto Morini, this is confirmed by our Vincent Glon:
and even in 1953, on a Gilera 500!
Actually Emilio Soprani survived the 05 May 1947 accident, and possibly he did not die in a racing accident. Or, it happened in 1954 or beyond.
What was the fate of Emilio Soprani?