Christensen T, Riis AH, Hatch EE, Wise LA, Nielsen MG, Rothman KJ, Toft Sorensen H, Mikkelsen EM. Costs and efficiency of online and offline recruitment methods: a web-based cohort study. J Med Internet Res. 2017 Mar 1;19(3):e58. doi: 10.2196/jmir.6716
Mangel AW, Williams VSL. Asimadoline in the treatment of irritable bowel syndrome. Expert Opin Investig Drugs. 2010 Oct 1;19(10):1257-64.
Phanikumar CV, Maitra B. Valuing urban bus attributes: an experience in Kolkata. J Public Transport. 2006;9(2):69-87. doi: 10.5038/2375-0901.9.2.4
Phani Kumar CV, Basu D, Maitra B. Modeling generalized cost of travel for rural bus users: a case study. J Public Transport. 2004;7(2):59-72. doi: 10.5038/2375-0901.7.2.4