Qual é a data do circuito de Zolder, que tinha a.z.k./roc-competition a.z.k./roc-competition como a equipa vencedora?
CREATE TABLE table_name_53 (date VARCHAR, winning_team VARCHAR, circuit VARCHAR)
SELECT date FROM table_name_53 WHERE winning_team = "a.z.k./roc-compétition a.z.k./roc-compétition" AND circuit = "zolder"