How to indicate in a class diagram that a field can refer to two directories?

Question

Database design

Hi all! There is an

entity "Repairs Performed" for the equipment:
Equipment: "Equipment" Directory
Date of repair: Date Type of repair
: Directory "types of repair" repairs can be performed by state organizations on their own , and this is a separate directory, an example of MBU "Repair Plant No. 1" repairs can be performed by private organizations, this is a separate directory, example: JSC "Service +" Question Please tell me how to indicate in the class diagram that the value can be two reference book???