How can I use EF Core to display data from 3 different tables in my application

I have 3 different tables, Customer, Vehicle, Contact.

The customer and vehicle tables share the common key ReferenceID and the customer and contact table share the key ContactID.

I want to be able to use EF core to display data from all three tables and was wondering if there is a way to do it without using JOIN?

Below is my attempt but I get this error: SqlNullValueException: Data is Null. This method or property cannot be called on Null values.

public class Customer
{
    public string Name { get; set; }
    [ForeignKey("Vehicle")]
    public string ReferenceID { get; set; }
    [ForeignKey("Contact")]
    public string ContactID { get; set;}
    public ICollection<Contact> Contact { get; set; }
    public ICollection<Vehicle> Vehicle { get; set; }
}

public class Vehicle
{
    public string ReferenceID { get; set;}
    public string Make {get; set;}
}

public class Contact
{
    public string ContactID {get; set;}
    public string Name {get; set;}
}