Draw the ER diagram

The following is the description of a hospital information database. As a large service organization, Valley Creek Community Hospital depends on a large number of persons for its continued success. There are four groups of people on whom the hospital is most dependent: Employees, Physicians, Patients, and Volunteers. (Physicians are not classified as Employees for the purpose of this project). There are several common attributes that are shared by all of these persons: Person_ID (unique identifier), Name, Birth_date, Phone, and Address. Each address can be accessed as Street_address, City, State, and Zip_code individually and the entire address can also be retrieved as a unit. Each of the four groups has at least one specific attribute of its own. Employees have a Date_hired, Volunteers have a Skill, Physicians have a Specialty and Pager\#, and Patients have a Contact_date. There might be additional personnel in the hospital community who do not belong to one of these four groups. A particular person may belong to more than one groups (for example, Patient and Volunteer). Each patient has one and only one physician responsible for them. A given physician may not be responsible for any patient or may be responsible for one or more patients. Patients are divided into two groups: inpatient and outpatient. Each patient classified as an inpatient has a Date_admitted attribute. Each patient classified as an outpatient is scheduled for one or more visits. Each visit has a Date (partial identifier) and Comments. Notice that a visit cannot exist without an outpatient entity. Employees are subdivided into three disjoint groups: Nurses, Staff, and Technicians. Nurses have a Certificate attribute that indicates the qualification. Staff has an attribute Job_class. Technicians have one or more Skills. Each technician is assigned to one or more laboratories. Attributes of laboratories include Name (unique identifier) and Location. A laboratory has one or more technicians assigned