Lapian, Stanss Levynna Hermien Verronica Joyce, and Altje Tumbel. “Analysis of Green Marketing Mix Factors On Hotel Industry (Study on Sintesa Peninsula Hotel Manado; Discovery Kartika Plaza Denpasar; Hyatt Regency Yogyakarta; Grand Melia Jakarta)”. International Review of Management and Marketing, vol. 8, no. 6, Jan. 2019, pp. 112-21, https://econjournals.com/index.php/irmm/article/view/7116.