Retnowati, Agung Tri. “Meningkatkan Pelayanan Konsumen Melalui Critical Perseption Point (CPP)”. Jurnal Computech & Bisnis (e-Journal), vol. 12, no. 1, June 2018, pp. 47-58, http://jurnal.stmik-mi.ac.id/jcb/article/view/127.