HELLER ROBERT. (1998). MOTIVATING PEOPLE. DORLING KINDERSLEY.
Lua i Stíl Chicago (17ú heag.)HELLER ROBERT. MOTIVATING PEOPLE. LONDON: DORLING KINDERSLEY, 1998.
Lua MLA (9ú heag.)HELLER ROBERT. MOTIVATING PEOPLE. DORLING KINDERSLEY, 1998.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.