Luciano JV, Barrada JR, Aguado J, Osma J, García-Campayo J. Bifactor analysis and construct validity of the HADS: a cross-sectional and longitudinal study in fibromyalgia patients. Psychological Assessment. 2014 Jun;26(2):395-406.
Goyal RK, Williams DH, Sansgiry SS, Essien J. Awareness and perceived usefulness of the website designed to facilitate informed health insurance purchase decisions. TPHJ. 2010 Jul;62(3):8-11.
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