CREATE TABLE table_10578 ("Year" FLOAT, "City" TEXT, "Rider 1" TEXT, "Rider 2" TEXT, "Horse 1" TEXT, "Horse 2" TEXT, "Association" TEXT)

With which association did estribillo ii run as Horse 1?
SELECT "Association" FROM table_10578 WHERE "Horse 1" = 'estribillo ii'
SELECT "Association" FROM "table_10578" WHERE "Horse 1" = 'estribillo ii'