The earliest known evidence of the phrase "spelling bee" in print dates back to 1850, although an earlier name, "spelling match", has been traced back to 1808. A key impetus for the contests was Noah Webster's spelling books. First published in 1786 and known colloquially as "The Blue-backed Speller," Webster's spelling books were an essential part of the curriculum of all elementary school children in the United States for five generations. Now the key reference for the contests is Webster's Third New International Dictionary.