CREATE TABLE table_15421 ("Year" FLOAT, "Entrant" TEXT, "Chassis" TEXT, "Engine" TEXT, "Points" FLOAT)

What entrant has a year earlier than 1960 and a veritas straight-6 engine?
SELECT "Entrant" FROM table_15421 WHERE "Year" < '1960' AND "Engine" = 'veritas straight-6'
SELECT "Entrant" FROM "table_15421" WHERE "Engine" = 'veritas straight-6' AND "Year" < '1960'