Callaghan, J. (1992). Costing for contracts. Directory of cocial change.
Chicago Style aipamenaCallaghan, John. Costing for Contracts. London: Directory of cocial change, 1992.
MLA aipamenaCallaghan, John. Costing for Contracts. Directory of cocial change, 1992.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.