Double/debiased machine learning for treatment and causal parameters, Victor Chernozhukov, Denis Chetverikov, Mert Demirer, Esther Duflo, Christian Hansen, Whitney Newey, and James Robins, 2018The Econometrics Journal, Vol. 21 (Wiley)DOI: 10.1111/ectj.12097 - Provides the theoretical foundation for Double Machine Learning, relevant for constructing pseudo-outcomes and robust ATE estimation in validation.