Hartley, B. (1984). Streamline english: Departures, part B: units 41-80 (5a. ed.). Oxford University Press.

Hartley, Bernard. Streamline English: Departures, Part B: Units 41-80. 5a. ed. New York: Oxford University Press, 1984.

Hartley, Bernard. Streamline English: Departures, Part B: Units 41-80. 5a. ed. Oxford University Press, 1984.