Hasan, Alizar, et al. “Analisis Hubungan Bauran Pemasaran Terhadap Keputusan Pembelian Smartphone Blackberry Dan Samsung Android”. Jurnal Optimasi Sistem Industri, vol. 13, no. 2, Apr. 2016, pp. 687–706, https://josi.ft.unand.ac.id/index.php/josi/article/view/300.