SELECT first_day_cover_cancellation FROM table_11900773_6 WHERE date_of_issue = "3 April 2008" AND theme = "IIHF World Championships, Quebec City"
Di mana pembatalan sampul hari pertama untuk Kejuaraan Dunia IIHF 3 April 2008, Stempel Kota Quebec?
CREATE TABLE table_11900773_6 (first_day_cover_cancellation VARCHAR, date_of_issue VARCHAR, theme VARCHAR)