edited by Hennig Cohen
Basic Book, 1969
Buku Teks
United States International Communication Agency , 1982
Buku Teks
United States International Communication Agency , 1982
Buku Teks
Pacey, Desmond
Ryerson Press, 1952
Buku Teks
Abel, Darrel
Barron's Educational Series, 1963
Buku Referensi