The WARREN BUFFETT WAY, by Robert G. Hagstrom, Jr.

The best system to value a business was determined more than seventy years ago by John Burr Williams in The Theory of Investment Value (North-Holland, 1938).
Paraphrasing Williams’s theory, Buffett tells us the value of a business is determined by the net cash flows expected to occur over the life of the business discounted at an appropriate interest rate.