CREATE TABLE table_4 ("No" FLOAT, "Date" CLOB, "Round" CLOB, "Circuit" CLOB, "Pole Position" CLOB, "Fastest Lap" CLOB, "Race winner" CLOB, "Report" CLOB)

Where was Assen held?
SELECT "Round" FROM table_4 WHERE "Circuit" = 'Assen'
SELECT "Round" FROM "table_4" WHERE "Circuit" = 'Assen'