I was wondering if you could guide me to a book that I can use as a starting point for preparing myself for graduate level econometrics. I will be applying for MA programs this fall and wanted a head start. I am currently reading Causal Inference: The Mixtape and honestly, I feel the book has some mistakes in proof and I do not really understand some of them. I do not know if it is due to my own wants but I would like to read another book that is more deeply explained. In addition if you have any references for statistics, such as where they show proofs for expectation properties and derivatives for matrices, I would be much obliged.