Expert
The authority of the PM comes from experience with the technology the project focuses on
Reward
The PM has the authority to reward the project team
Formal
The PM has been assigned by senior management and is in charge of the project. Also known as positional power
Coercive
The PM has the authority to discipline the project team members. Also known as penalty power
Referent
The project team personally knows the PM. Can also mean the PM refers to the person who assigned him the position