Research Question Alert - Help!

All you railroad buffs out there - I need help and the Internet apparently has no idea what I'm talking about.

European railroad cars pre-WWI (1911, to be exact). I know first-class were compartments, each entered separately from the platform. What about third-class? Was it a Pullman-style, single chamber with benches? Or was it just grubbier compartments that anyone could get into? And, where would I find this information? Is there any site anyone knows about that has a (gasp!) layout of trai...