Tong, Anh B, Javier Calvo, and Karl Haapala. 2019. “Integration of Sustainability Performance Indicators and the Viable System Model Toward a Systemic Sustainability Assessment Methodology”. Proceedings of the 61st Annual Meeting of the ISSS - 2017 Vienna, Austria 2017 (1). https://journals.isss.org/index.php/proceedings61st/article/view/3131.