Watson, Lee
McGraw-Hill, 1990
Buku Referensi
Anggia Agri Shafira
Fakultas Teknik Universitas Indonesia, 2020
UI - Skripsi (Membership)
Pritchard, David C.
Longman, 1995
Buku Teks
Pritchard, David C.
Longman, 1995
Buku Teks
Lisgumantika Suha
2014
UI - Skripsi (Membership)