Zeng, An
Shen, Zhesi
Zhou, Jianlin
Fan, Ying
Di, Zengru
Wang, Yougui
Stanley, H. Eugene
Havlin, Shlomo
Article History
Received: 13 January 2019
Accepted: 9 July 2019
First Online: 31 July 2019
Competing interests
: The authors declare no competing interests.