Design a database to hold the contractual data of a rental company. Every contract covers the following: 

1. data about the client (client number, name and phone); 
2. data about the property (property number, address, and owner);
3.  parameters of the contract: period - dates of start and end, and the amount the clients pays. 
4. Owner is described by owner number, name, and phone. 

Notes:

1.  one client may rent several properties;
2.  one owner may own several properties. 

Design outcomes are ER model and database relational schema normalized to 3NF/BCNF.