Gaya APA

Hamp-Lyons, L., Ben, I, H. (NULL). Study writing a course in written english for academic and professional ì purposes . London:: London: Cambridge University; 1987.

Gaya MLA

Hamp-Lyons, Liz., Ben, I., Heasley,. "Study writing a course in written english for academic and professional ì purposes". London:: London: Cambridge University; 1987, NULL. Text.