YouTube the Milan Dvorak jazz etudes there are two books of them and they are progressive ( in concepts not necessarily in technical demand as a few of book 1 are harder to pull off than later ones )and playin through both volumes will help familiarize you w the idiom while keeping the learning curve low.
The of course Kapustin.
Also get some Dave Brubeck books especially his nocturnes.
There is tons if stuff and I'll truth post some and more as aside from Soviet and Balkans region classical. This happens to be am area of keen interest to me so I have lots and lots of examples in my archives and favorites feed on the tube. Pending. Stay tuned
Oh FYI here is one of funnest of the Dvorak
( reminds me I should start these up again soon)
There is a great little book use inconclusive avail from Japan but Alfred released a us version ( not as good but still better than ok). Th super Mario jazz tunes a re a great place to practice gettin your chops built
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