Mangel AW, Fehnel SE. End points in irritable bowel syndrome. Expert Rev Gastroenterol Hepatol. 2011 Jun 1;5(3):293-5.
Phanikumar CV, Maitra B. Modeling willingness-to-pay values for rural bus attributes under different trip purposes. JTRF. 2006;45(2):31-44. doi: 10.22004/ag.econ.206787
Dreyer NA, Loughlin JE, Rothman KJ. Epidemiologic safety surveillance of cellular telephones in the US. Radiat Prot Dosimetry. 1999 Jun;83(1):159-63.