user: Question: What Social AO has an External CO of Elena Buscher, and a President of Harm van Leeuwen?
Columns: ['President', 'Treasurer', 'Secretary', 'Social AO', 'Academic AO', 'Internal CO', 'External CO']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Caroline Mattias', 'Florian Simonsen', 'Menno Reijven', 'Christine Baljet', 'Arno Angerer', 'Jan Meijer', 'Elina Muceniece']
SQL:

assistant: SELECT "Social AO" FROM "Table" WHERE "External CO" = 'Elena Buscher' AND "President" = 'Harm van Leeuwen';