APA Style
Pandjaitan,Dipl.Ing.Petro, I.
(1992).
longman introductory course for the toefl test
.
america:
Longman.
MLA Style
Pandjaitan,Dipl.Ing.Petro, Ir.Maraudin.
"longman introductory course for the toefl test".
america:
Longman,
1992.
Buku PGSD.