CREATE TABLE table_name_26 (league VARCHAR2, established VARCHAR2, club VARCHAR2)

What is the league established before 1930 with the rayo vallecano club?
SELECT league FROM table_name_26 WHERE established < 1930 AND club = "rayo vallecano"
SELECT "league" FROM "table_name_26" WHERE "club" = "rayo vallecano" AND "established" < 1930