Most corner cupboards involve a double door arrangement. You can do it with 170 degree concealed hinges on one side with either piano hinge or appropriate concealed hinges connecting the two doors.

You can also do it by 170 degree hinging both doors on their respective end panels. You end up with a handle on one door which you open first and then open the other simply by putting your hand behind the door stile to pull it open.

You can also get Susan's for blind corners where you only have one door. I have always avoided this as a deliberate design as I would hate to try and clean a cupboard like this or find a small item that fell off the shelf.

Hardware for corner units is purchased from the same suppliers as standard hinges. Suppliers like the ones already mentioned have detailed catalogues which set out all the measurements and allowances for using their hardware. Cheers