How to notate this relationship

Hi there,

In the attachment there are two classes Item ansd Ledger.

Buiness rule say that :

  1. “Ledger” can have maximum of 12 “Item” objects
  2. In each “Item” object in the “Ledger” there can be maximum of 20 of the same item


  1. What kind of relationship is this?
  2. How do i put this in the class Diagram and how the references should be included into the classes?