1. Instrumental variables in action: sometimes you get what you need;Angrist;Mostly Harmless Econ. Empiricist's Companion,2009
2. Anon. China’s National Bureau of Statistics, China Environmental Statistical Yearbook, (2021). https://www.yearbookchina.com/navibooklist-n3022042109-1.html.
3. Anon. State Intellectual Property Office of China (SIPO), (2022). Patent Information Service Platform. http://search.cnipr.com/.
4. Anon. China National Knowledge Infrastructure. China Construction Industry Statistical Yearbook, (2022). https://data.cnki.net/v3/trade/Yearbook/Single/N2023010136?zcode=Z005.
5. Anon. China's National Bureau of Statistics. China Statistical Yearbook, (2022a). http://www.stats.gov.cn/sj/ndsj/2022/indexch.htm.