Ngoc, Nguyen
Foreign Languages Publishing House, 1961
Koleksi Publik
Lala Maya Sabrina
Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia, 2016
UI - Makalah dan Kertas Kerja
Bocchetta, Vittore E.
Follett Publishing Company, 1987
Buku Referensi
Clark, Martin
Longman, 1998
Buku Teks SO
Sabino, Catherine
Thomes and Hudson, 1986
Buku Referensi