Audiobooks on Ipod Classic 160GB

I have some audiobooks in my iTunes, organised into different books, each separated into chapters (20-30 minute mp3 tracks, just changed to media type "audiobook").

They are all fine, and remain grouped together as books in my iTunes, but not on my iPod. When I open the Audiobooks section on my iPod, the chapters from various books appear, all jumbled and random, impossible to listen to in sequence.

I have no problem playing through them on my iTunes, but cannot figure out how to group them into folders etc. on my iPod.

I'd be very grateful for some advice, thank you.