NeXTSTEP OS on Virtualbox?

Hey, I want to emulate NeXTSTEP OS (NeXT) on Virtualbox. I have an iso file of NeXT but it fails to boot. I think I need floppy disk files to boot it, however I don't know where to find them. I've searched for hours now. So if I can run from the iso that would be awesome, but if you can direct me somewhere else that would be great too!

Cheers,

Adam

PS
Sorry this is under Classic Mac OS, there is no NeXT category, but Apple owns NeXT so I thought I'd start here.