IFR training
I first bought the Jepp book (big text book looking thing). It is exactly that... A text book. Very dry and boring to read, but great information. I didn't do very well with that, so I bought the King DVD series. I had used the King's for my private, so I was familiar with their format. I know it's a little pricey, but for my money, there is no better training aid. I do keep the Jepp book handy as a reference, and I use it for recurrent learning.
Dave