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_91 ( retired VARCHAR, notes VARCHAR )

### Question ###
What year was the aircraft retired when it was replaced by 737-300s?

### Accurate SQL ###

SELECT retired FROM table_name_91 WHERE notes = "replaced by 737-300s"