CREATE TABLE table_name_56 (tournament VARCHAR2, margin_of_victory VARCHAR2, date VARCHAR2)

What is the name of the tournament played on Sep 20, 1981, ending with a margin of vicroty of 2 strokes?
SELECT tournament FROM table_name_56 WHERE margin_of_victory = "2 strokes" AND date = "sep 20, 1981"
SELECT "tournament" FROM "table_name_56" WHERE "2 strokes" = "margin_of_victory" AND "date" = "sep 20, 1981"