Musicians in general and jazz musicians in particular:
Do you wonder what's the best and fastest way to internalize polyrhythms of 2 against 3?
This eBook has all the possible permutations laid down (56) along with play-along tracks so you can not only "hear" how each pattern sounds like, but also practice against any line you want as each track is recorded on a separate channel.
The eBook is called "Duple VS Triple: A Melodic Approach to Mastering Polyrhythms in Jazz and Other Groove-Based Music in 56 Steps" and it's available for digital download at the website below for $9.
Preview and listen to samples here: http://www.tarekyamani.com