CREATE TABLE table_27408 ("Book series" TEXT, "Author" TEXT, "Original language" TEXT, "No. of installments" TEXT, "First published" TEXT, "Approximate sales" TEXT)

What is every original language for book series Little House on the Prairie?
SELECT "Original language" FROM table_27408 WHERE "Book series" = 'Little House on the Prairie'
SELECT "Original language" FROM "table_27408" WHERE "Book series" = 'Little House on the Prairie'