Lewis, W. (1970). Overhead costs (3rd.). Unwin Univ.
Lua i Stíl Chicago (17ú heag.)Lewis, W. Overhead Costs. 3rd. London: Unwin Univ, 1970.
Lua MLA (9ú heag.)Lewis, W. Overhead Costs. 3rd. Unwin Univ, 1970.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.