Conversation so far:
Has Rosa Ponselle ever perfomed overseas?
Outside the USA, Rosa Ponselle sang only at Covent Garden in London and in Italy.
What year did Rosa Ponselle begin to perform in London?
In 1929, Rosa Ponselle made her European debut in London, at the Royal Opera House at Covent Garden.

Question: When did she finish her career?
Self-contained rewrite: When did Rosa Ponselle finish her career?