APA
Alexander D., . (1993). Study Guide for Speaking Professional Module 3 Lesson 15-17. USA: Lingua Marketing International.
Chicago
Alexander D.L, . 1993. Study Guide for Speaking Professional Module 3 Lesson 15-17. USA: Lingua Marketing International.
Harvard
Alexander D., . (1993). Study Guide for Speaking Professional Module 3 Lesson 15-17. USA: Lingua Marketing International.
MLA
Alexander D.L, . Study Guide for Speaking Professional Module 3 Lesson 15-17. USA: Lingua Marketing International. 1993.