The hospital need to keep track the patient details whenever a patient arrives in the hospital for a check up. When patient arrives, patient details like name, age, sex, address, city, phone number, entry date, name of the doctor referred to, diagnosis, and department name are also stored. After storing the necessary details patient is sent to the doctor for check up. Patient number should begin with prefix PT. Sex should be M or F only. The referred doctors name and department referred must exist. The details about the patients who get treatment from the doctor referred to is required to be recorded. Details like patient number, doctor number, date of check up, diagnosis, and treatment are stored. One more field status is used to indicate whether patient is admitted, referred for operation or is a regular patient to the hospital. For these three types of patient, patient details are stored in three different tables. When additional doctors are called by the hospital, the information required to be recorded includes their doctor number and other personal details like name, qualification, fees per call, payment due, address, phone number, etc.

Help me draw an Entity Relationship Diagram.

Please use crow foot notation