6James M Buchanan, Robert D.Tollison.The Theory of Public Choice, Uni- versity of Michigan Press, Michigan, 1972.
7Regulation on Travel Expense and Reimbursement (Applies to travel ex- penses incurred on and after November 23,2004) ,Commonwealth of Kentucky, Finance and Administration Cabinet, Office of the Controller.
8Joseph.Stiglitz.Economics of the Public Sector, N.W.Norton, New York, 2002.