CREATE TABLE table_24076 ("Episode" TEXT, "Broadcast date" TEXT, "Run time" TEXT, "Viewers  ( in millions ) " TEXT, "Archive" TEXT)

What is the archive of the show that aired on 18april1970?
SELECT "Archive" FROM table_24076 WHERE "Broadcast date" = '18April1970'
SELECT "Archive" FROM "table_24076" WHERE "Broadcast date" = '18April1970'