Artikel Jurnal
Collins, Lawrence, author
Butterworth, 1990
Buku Teks
London: Her Majesty's Stationary office, 1987,
Buku Referensi
Stephens-Davidowitz, Seth, author
Gramedia Pustaka Utama, 2018
Buku Teks
Duhigg, Charles, author
KPG (Kepustakaan Populer Gramedia), 2016
Buku Teks