Iroth, Yosie, and Judith Sinaga. “Expectancy Theory As A Determination Of Net Promoter Score (Nps): Increasing The NPS Value Of Services”. EKOMBIS REVIEW: Jurnal Ilmiah Ekonomi dan Bisnis 12, no. 3 (July 10, 2024): 2741–2746. Accessed November 21, 2024. https://jurnal.unived.ac.id/index.php/er/article/view/5438.