Sianipar, Marisa. “Effect of Product, Price, Location and Tourism Promotion of Interest in Visiting Lake Toba Tourist Attraction”. Enrichment : Journal of Management 9, no. 2, May (May 1, 2019): 18-22. Accessed April 29, 2024. http://enrichment.iocspublisher.org/index.php/enrichment/article/view/11.