Callaghan, J. (1992). Costing for contracts. Directory of cocial change.
Lua i Stíl Chicago (17ú heag.)Callaghan, John. Costing for Contracts. London: Directory of cocial change, 1992.
Lua MLA (8ú heag.)Callaghan, John. Costing for Contracts. Directory of cocial change, 1992.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.