Book lists are always the usual American,Anglo,Axis lists. Shame there isn't more available from Soviet,Japanese,Italian etc.
<S>...-Gixer
It's there, you just have to look a bit harder to find it.  I suppose it has to do with wanting to actually sell some copies.  The folks interested in the other stuff you mention are a much smaller group.  You tend to find info on those birds in more general books.
There is a guy named George Mellinger who is from the Twin Cities that has always been a Soviet AF junkie.  He's done some of the Osprey stuff on Soviet aces.  I know he's done a lot of articles on them too.
There is a website out there that is nothing but Japanese WW2 Aviation.
It all comes down to how hard you want to look in the end, though I would agree it's harder to find the stuff you are interested in.