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_47 (date VARCHAR, winning_driver VARCHAR, circuit VARCHAR)

### Question ###
What is the date of the circuit of nürburgring, which had Graham Hill as the winning driver?

### Accurate SQL ###

SELECT date FROM table_name_47 WHERE winning_driver = "graham hill" AND circuit = "nürburgring"