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
Bonfill X, Rivero E, Moreno C, Rué M. Changes in cancer mortality in Catalonia and Spain (1975-77 and 1987-89). A comparison with other European countries. Eur J Cancer Prev. 1995 Dec;4(6):453-8.