APA (7th ed.) Citation

Gray, J., Farris, D., Cousins, G., Warburton, B., & Gayes, P. (1991). Discovering English: A pre-intermediate course (1. vyd.). Mladex.

Chicago Style (17th ed.) Citation

Gray, Joanna, David Farris, Gerry Cousins, Bob Warburton, and Paul Gayes. Discovering English: A Pre-intermediate Course. 1. vyd. Bratislava: Mladex, 1991.

MLA (9th ed.) Citation

Gray, Joanna, et al. Discovering English: A Pre-intermediate Course. 1. vyd. Mladex, 1991.