Walsh, J. (1987). The manager`s problem solver. Spherell.
Chicago Style aipamenaWalsh, John. The Manager`s Problem Solver. London: Spherell, 1987.
MLA aipamenaWalsh, John. The Manager`s Problem Solver. Spherell, 1987.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.