Draw an entity-relationship diagram for the following case.

The United Nations wants to develop a global database, tracking countries, cities, and multinational companies. For each country, the UN wants to store its name, capital, population, and the name of its head of state. The UN assigns each city in the world a unique, global, numeric identifier. It also wants to record the city's name, the name of the city’s mayor (or chief executive), its population, and its size in square miles. Obviously, a city is associated with only one country. Each city has many employees. Each employee has an employee number unique to that city, plus a name and date of birth. Some employees of a city manage other employees of that city. Each city also has city-owned buildings. Each building a city owns has a type (fire station, police station, etc.) an address (its unique identifier), and the year it was built. Each multinational company has a globally unique identifier, a name, a president, and the year it was founded. Obviously, a country has many companies operating in it and, by definition, a multinational company can operate in more than one country. The UN wants to keep track of how much revenue each company generated each year in each country in which it operates. 

This is an Example on how it should look like :

CUSTOMER PK Customer ID PRODUCT LINE Customer Name Customer Address Customer Postal Code PK Product Line ID Product Line Name I Submits ORDER Includes PK Order ID sta Order Date PRODUCT ORDER LINE PK Product ID Product Description Product Finish md Product Standard Price budbe Ordered Quantity VENDOR USES PRODUCED IN PK Vendor ID Vendor Name Goes Into Quantity Vendor Address AVE RAW MATERIAL SUPPLIES PK Material ID WORK CENTER PK Work Center ID Material Name Material Standard Cost Unit Of Measure Supply Unit Price iw Work Center Location Is Supervised By EMPLOYEE Supervises WORKS IN O PK Employee ID SKILL HAS SKIL