It's time for Roberto Clemente's No. 21 to be retired across baseball - Bucs Dugout

Puerto Rican Twins don No. 21 in tribute to Roberto Clemente – Twin Cities

Javier Báez on Roberto Clemente Day

December 31: ¡Arriba Roberto! - Sports Illustrated Vault

Roberto Clemente's No. 21 is 'retired in our hearts' but not on most MLB rosters - The Athletic

MLB gets it right with Roberto Clemente No. 21 jersey policy

Retire 21: Supporters Seek To Honor Baseball Legacy Of Roberto Clemente

Tell MLB to retire Roberto Clemente's number