Hahn, Dale B.
McGraw-Hill, 2002
Buku Teks
Bullock, Barbara
Lippincott , 2000
Buku Teks
Berman, Harold J.
Little, Brown, 1953
Buku Teks
Ministry of Foreign Affairs Netherlands, Communication Division (DVL/VB) ,
Buku Teks
Thich, Nhat Hanh
Parallax Press, 2022
Buku Teks