CREATE TABLE table_name_68 (year INT, entrant VARCHAR, chassis VARCHAR)

What was the sum of the years, when the entrant was Scuderia Ferrari, and when the Chassis was Ferrari 312/66?
SELECT SUM(year) FROM table_name_68 WHERE entrant = "scuderia ferrari" AND chassis = "ferrari 312/66"
SELECT SUM("year") FROM "table_name_68" WHERE "chassis" = "ferrari 312/66" AND "entrant" = "scuderia ferrari"