Hartley, B. (1985). Streamline english: Departures, part A: units l-40 (9a. ed.). Oxford University Press.

Hartley, Bernard. Streamline English: Departures, Part A: Units L-40. 9a. ed. New York: Oxford University Press, 1985.

Hartley, Bernard. Streamline English: Departures, Part A: Units L-40. 9a. ed. Oxford University Press, 1985.