Anggia, Feliks, Ubud Salim, Sunaryo Sunaryo, and Solimun Solimun. 2017. “Moderation of Personal Relations on Sustainable Competitive Advantages, Customer Relationship Management, and Marketing Performance: Study on Small Scale Business of Leather Products Marketers in East Java”. International Review of Management and Marketing 7 (4):74-82. https://econjournals.com/index.php/irmm/article/view/5135.