Euriga, Epsi, et al. “The Motivation Factors and Farmer Group Clusters on Sustainable Horticulture Practices Adoption in Yogyakarta Province”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 38, no. 2, May 2018, pp. 160-71, https://gssrr.org/JournalOfBasicAndApplied/article/view/8974.