The rights of ghostwritting

[veltox]

Greetings. I have a horror ghostwritting gig that I wish to expand and I have one much needed question. 
In the "Gallery" Section of "Edit Gig" I see the options of featuring past images and documents from my previous work. 
As a ghostwritter do I have the right to feature the entirety of certain stories from my past clients despite the fact I don't own the right to sell them for myself anymore?
I wish to avoid any legal issues as much as possible and want to know what I can and can't do. 

[joyh97]

If you have expressed full transfer of all ownership to clients, then you probably can't use the work to advertise your own services without express permission, so it's best to avoid the risk in my opinion.

Your best bet is to ask your previous clients if they're ok with it, or write something fresh for illustrative purposes that you have full rights to.