Using the Crows Foot methodology and Erwin Data Modeler, create an ERD that can be implemented for a medical clinic, using at least the following business rules:

1. A patient can make many appointments with one or more doctors in the clinic.

2. A doctor can accept appointments with many patients. However, each appointment is made with only one doctor and one patient.

3. Emergency cases do not require an appointment. However, for appointment management purposes, an emergency is entered in the appointment book as unscheduled.

4. If kept, an appointment yields a visit with the doctor specified in the appointment. Each visit is recorded by only one doctor and attended by only one patient.

5. With each visit, the patients medical history is updated. One patient must and only have one medical history.

6. Each medical history can have many medical records.

7. Each patient visit must create a bill.

8. Each patient visit must generate a medical record.