Kim D, Lauria DT, Poulos C, Dong B, Whittington D. Effect of travel distance on household demand for typhoid vaccines: implications for planning. Int J Health Plann Manage. 2013 Mar 12;Advance Online.
Reed (Earnshaw) SR, Reed JH, Stuhldreher TJ. Transaction costs, taxes, and portfolio revision. J Contemp Bus Issue. 1997;5:40-8.