Howes, V. E. (1967). Pre-calculus mathematics: A programmed text. John Wiley and Sons, Inc.
Lua i Stíl Chicago (17ú heag.)Howes, Vernon E. Pre-calculus Mathematics: A Programmed Text. New York: John Wiley and Sons, Inc, 1967.
Lua MLA (9ú heag.)Howes, Vernon E. Pre-calculus Mathematics: A Programmed Text. John Wiley and Sons, Inc, 1967.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.