Jushan Bai. 2009. "Panel Data Models with Interactive Fixed Effects." Econometrica.
Yiqing Xu. 2017. "Generalized Synthetic Control Method: Causal Inference with Interactive Fixed Effects Models." Political
Analysis.
Athey, Susan, et al. 2021 "Matrix completion methods for causal panel data models." Journal of the American Statistical Association.
Licheng Liu, et al. 2022. "A Practical Guide to Counterfactual Estimators for Causal Inference with Time-Series Cross-Sectional
Data." American Journal of Political Science.
For more details about the matrix completion method, see https://github.com/susanathey/MCPanel.