Spencer, L. M. (1993). Competence at Work (11th.). McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Spencer, Lyle M. Competence at Work. 11th. Singapore: McGraw-Hill, 1993.
Lua MLA (9ú heag.)Spencer, Lyle M. Competence at Work. 11th. McGraw-Hill, 1993.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.