Poltak Pardamean Simarmata, Doris Yolanda Saragih, and Hengki Mangirng Parulian Simarmata, “Green Material & Process and Green Packaging as Drivers of Tourists’ Sustainable Purchase Intention: Evidence from a PLS-SEM Study in Lake Toba, Indonesia”, makreju, vol. 4, no. 3, pp. 106–128, Aug. 2026.