CREATE TABLE table_30052 ("Round" TEXT, "Main date" TEXT, "Number of fixtures" FLOAT, "Clubs" TEXT, "New entries this round" TEXT, "Prize money" TEXT, "Player of the Round" TEXT)

what is the club in the sixth round proper
SELECT "Clubs" FROM table_30052 WHERE "Round" = 'Sixth round proper'
SELECT "Clubs" FROM "table_30052" WHERE "Round" = 'Sixth round proper'