Research on the Correlation Between Energy Reform and City Development Based on Cointegration and Causality Analysis Part 1 The correlation analysisYan Zhang, Zhenwei Li, Zhe Xie, Luxin Zhao, Chen Zhang and Xinyang HanE3S Web Conf., 218 (2020) 02034DOI: https://doi.org/10.1051/e3sconf/202021802034