Siami-Namini, Sima. “Granger Causality Between Gross Domestic Product and Economic Sectors in Developing Countries: A Panel Co-Integration Approach”. International Journal of Economics and Financial Issues, vol. 7, no. 5, Oct. 2017, pp. 53-58, https://mail.econjournals.com/index.php/ijefi/article/view/5229.