Parker, John, author
Headline, 2005
Buku Teks
Harding, Luke, 1968-, author
Guardian, 2016
Buku Teks
Harding, Luke, author
Gagas Bisnis, PT Bisnis Indonesia Gagasreasitama, 2015
Buku Teks
Volpe, S. Peter (Sonnino Peter), 1917-, author
Wiley-Interscience, 1972
Buku Teks
Phoenix Publishing Limited, 2011
Buku Referensi