CREATE TABLE table_52599 ("Stage" TEXT, "Winner" TEXT, "General classification" TEXT, "Points classification" TEXT, "Trofeo Fast Team" TEXT)

Which stage has a Winner of lucien van impe?
SELECT "Stage" FROM table_52599 WHERE "Winner" = 'lucien van impe'
SELECT "Stage" FROM "table_52599" WHERE "Winner" = 'lucien van impe'