"Warren Buffett has learned that companies that have a durable competitive advantage often carry little or no long-term debt on their balance sheets. This is because these companies are so profitable that they are self-financing when they need to expand the business or make acquisitions, so there is never a need to borrow large sums of money."   Mary Buffett and David Clark in "Warren Buffett and the Interpretation of Financial Statements" 

     "It makes no sense that the values of most companies swing wildly from high to low, or low to high, during the course of each and every year.  On the other hand, it seems pretty clear that the prices of the shares in most companies swing around wildly each and every year."  Joel Greenblatt in "The Little Book that Beats the Market"

     "Warren Buffett's historic purchases indicate that on any given year the company should have sufficient yearly net earnings to pay off its long-term debt within a three- or four-year earnings period."   Mary Buffett and David Clark in "Warren Buffett and the Interpretation of Financial Statements"

     "Over the last 17 years, owning a portfolio of approximately 30 stocks that had the best combination of a high return on capital and a high earnings yield would have returned approximately 30.8% per year."  Joel Greenblatt in "The Little Book that Beats the Market"