I don't know of anything specific as ES is basically a VAR calc where you average the tail rather than take the 99 percentile point. I thought the Basel paper covered that.I am going through the new FRTB regulations and need to understand the Internal Modeling Approach (IMA). Are there any good research papers/books/Videos that can explain the Expected Shortfall calculations, P&L attribution test and Backtesting with a case study approach (using some actual data)? Please suggest.