Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_39 ( social_ao VARCHAR, external_co VARCHAR, president VARCHAR )

### Question ###
What Social AO has an External CO of elena buscher, and a President of harm van leeuwen?

### Accurate SQL ###

SELECT social_ao FROM table_name_39 WHERE external_co = "elena buscher" AND president = "harm van leeuwen"