Gaya APA
Sembiring, J., Coventri, P. (1986).
Toefl A Practical Approach; Book one Structure and Written Expressions .
Jakarta:
Bina Cipta.
Gaya MLA
Sembiring, Jafar., Coventri, Philip.
"Toefl A Practical Approach; Book one Structure and Written Expressions".
Jakarta:
Bina Cipta,
1986.
Textbook.