Crosby, P. B. (1979). Quality is free: The art of making quality certain. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Crosby, Philip B. Quality Is Free: The Art of Making Quality Certain. New York: McGraw-Hill, 1979.
Lua MLA (9ú heag.)Crosby, Philip B. Quality Is Free: The Art of Making Quality Certain. McGraw-Hill, 1979.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.