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_8 ( source VARCHAR, date VARCHAR, race_winners VARCHAR, gp_winner VARCHAR )

### Question ###
What source has a race winner of ben adriaenssen / ben van den bogaart, and the gp winner of ben adriaenssen / ben van den bogaart, for the date of 1 april?

### Accurate SQL ###

SELECT source FROM table_name_8 WHERE race_winners = "ben adriaenssen / ben van den bogaart" AND gp_winner = "ben adriaenssen / ben van den bogaart" AND date = "1 april"