CREATE TABLE table_name_39 (social_ao VARCHAR2, external_co VARCHAR2, president VARCHAR2)

What Social AO has an External CO of elena buscher, and a President of harm van leeuwen?
SELECT social_ao FROM table_name_39 WHERE external_co = "elena buscher" AND president = "harm van leeuwen"
SELECT "social_ao" FROM "table_name_39" WHERE "elena buscher" = "external_co" AND "harm van leeuwen" = "president"