Flesch, R. (1951). How to test readability ([First edition].). Harper.
Chicago Style (17th ed.) CitationFlesch, Rudolf. How to Test Readability. [First edition]. New York: Harper, 1951.
MLA (9th ed.) CitationFlesch, Rudolf. How to Test Readability. [First edition]. Harper, 1951.
Warning: These citations may not always be 100% accurate.