CREATE TABLE table_4568 ("Higher harmonics" TEXT, "Darwin" TEXT, "Period" TEXT, "Speed" TEXT, "Doodson coefficients" TEXT, "NOAA" TEXT)

What is the NOAA of the higher harmonics that have a Darwin of m sf?
SELECT "NOAA" FROM table_4568 WHERE "Darwin" = 'm sf'
SELECT "NOAA" FROM "table_4568" WHERE "Darwin" = 'm sf'