Create the initial ER diagram for a car dealership. The dealership sells both new and used cars, and it operates a service facility. Base your design on the following business rules:

a. A salesperson can sell many cars but each car is sold by only one salesperson.

b. A customer can buy many cars but each car is sold to only one customer.

c. A salesperson writes a single invoice for each car sold.

d. A customer gets an invoice for each car (s)he buys.

e. A customer might come in just to have a car serviced; that is, one need not buy a car to be classified as a customer.

f. When a customer takes one or more cars in for repair or service, one service ticket is written for each car.

g. The car dealership maintains a service history for each car serviced. The service records are referenced by the car's serial number.

h. A car brought in for service can be worked on by many mechanics, and each mechanic may work on many cars.

i. A car that is serviced may or may not need parts. (For example, parts are not necessary to adjust a carburetor or to clean a fuel injector nozzle.)