Text book recommendation: This course does not follow a textbook, but a good reference is All of Statistics: A Concise Course in Statistical Inference, by Larry Wasserman.
Aditya’s note on 18.6501x
Fundamentals of Statistics(18.6501x)
Jokerdii’s note on 18.6501x
YolandaHT’s note on 18.6501x (hand writing)
https://github.com/Yolanda-HT/MIT_18.6501x/blob/master/MITx_18.6501_Stats_Notes_Yolanda.pdf
https://www.davidkhachatrian.com/assets/pdf/notes/Fundamentals of Statistics (18.6501x).pdf