It is always handy if you know what you can get from bosses. Here you can find drop list for CZ bosses, Eslant bosses, Felankor and Isiloon.
Bosses from Chaos stone have shared drop list, which means, that you should be able to drop everything from everyone, just with different probabilities.
However it has been changed many times in the past and developers never released official drop list. It means, that information found here are observed by players and so it hasn't be 100% correct.
Actual state is that all bosses can drop everything except few items which can be dropped only by specific bosses.