Khan Academy
Khan Academy: Present Value: Time Value of Money
Why the time that you get your money matters as much as how much money you get. Present and future value also discussed.
Khan Academy
Khan Academy: Present Value: Present Value 2
Discusses a variety of choices as to when money is given to someone, and which one - present or future - is the best value for the money. [10:11]
Investopedia
Investopedia: Unlevered Beta
Learn about how this calculation provides a number of how much systematic risk a firm's equity has compared to the market.