Where are my purchased audiobooks on iPad

If you've purchased and downloaded them or synced them to the iPad then you should have an Audiobooks option under the More button at the bottom of the Music app (that option will only appear if there are audiobooks in it)

They are not there. When I select MORE, all I get are categories.

Are you sure that your audiobooks are on your iPad ? Did you buy and download them directly on it or have you tried to sync them from your computer'e iTunes ?