Roberto Clemente's No. 21 is 'retired in our hearts' but not on most MLB rosters - The Athletic
Roberto Clemente Day to Be Held Throughout MLB on Thursday – NBC 6 South Florida
Celebrating Roberto Clemente day : r/baseball
Roberto Clemente, Pittsburgh's Hero
All Puerto Rican players can wear 21 on Clemente Day
Pirates will honor Roberto Clemente by wearing his No. 21 on their jerseys - ESPN
To Honor Roberto Clemente, MLB Expands List of Who Can Wear No. 21 - Sports - Remezcla
MLB allows more players to wear No. 21 to honor Roberto Clemente – NBC Sports Chicago
For the 'Great One'; Pirates, MLB honor Roberto Clemente
All Pirates Wearing #21, Rest of MLB Wears Patches in Honour of Roberto Clemente – SportsLogos.Net News
Why are MLB players wearing 21? Tributes around the league for Pirates legend explained
Roberto Clemente Day: Brent Suter celebrates MLB legend, wears No. 21