CREATE TABLE table_58980 ("Outcome" TEXT, "Date" TEXT, "Championship" TEXT, "Surface" TEXT, "Opponent in the final" TEXT, "Score in the final" TEXT)

What Surface has a Date of 15 february 1988?
SELECT "Surface" FROM table_58980 WHERE "Date" = '15 february 1988'
SELECT "Surface" FROM "table_58980" WHERE "Date" = '15 february 1988'