I have an economics degree, but feel I've learned more from his shareholder's letters than 4 years of university. So I too recommend them.

The letters starting from 1995 can be consulted at http://www.berkshirehathaway.com/reports.html.

They are also available in book form 'Berkshire Hathaway Letters to Shareholders', starting from 1965 (with the early partnership letters).

Charlie Munger's Wesco Letters to Shareholders are also interesting, especially the early ones: http://www.wescofinancial.com/.