CREATE TABLE table_11900773_6 (first_day_cover_cancellation VARCHAR(255), date_of_issue VARCHAR(255), theme VARCHAR(255))
Where is the first day cover cancellation for the 3 April 2008 IIHF World Championships, Quebec City stamp?
    
SQL: SELECT first_day_cover_cancellation FROM table_11900773_6 WHERE date_of_issue = "3 April 2008" AND theme = "IIHF World Championships, Quebec City"