In the circuit Showevent Olympiastadion München, where the winning driver is Bruno Spengler, what is the pole position?
create table table_26267607_2 (pole_position varchar, winning_driver varchar, circuit varchar, PRIMARY KEY (pole_position))
select pole_position from table_26267607_2 where winning_driver = "bruno spengler" and circuit = "showevent olympiastadion münchen"