Prominent Soviet-era dissident, poet, and mathematician Aleksandr Yesenin-Volpin has died in the United States aged 91.
Russian media reports cited Yesenin-Volpin's friends as saying that the veteran dissident, who was a son of Russia's most celebrated poet of the 1920s, Sergei Yesenin, died on March 16.
Yesenin-Volpin became known for his poems challenging the Soviet system, spending in total 14 years in Soviet jails and psychiatric clinics.
He was one of the organizers of the first public protest in the postwar Soviet Union in 1965, demanding transparency in the trial against Soviet writers Andrei Sinyavsky and Yuly Daniel.
Four years after his last incarceration in a psychiatric clinic in 1968, Yesenin-Volpin left the Soviet Union for the United States.