Warttig SL, Forshaw MJ, South J, White AK. New, normative, English-sample data for the Short Form Perceived Stress Scale (PSS-4). J Health Psychol. 2013 Dec;18(12):1617-28. doi: 10.1177/1359105313508346
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.