The Descriptive Epidemiology of Sitting A 20-Country Comparison Using the International Physical Activity Questionnaire (IPAQ) - Bauman A; Ainsworth BE; Sallis JF; Hagströmer M; Craig CL; Bull FC; Pratt M; Venugopal K; Chau J; Sjöström M; IPS Group (American Journal of Preventive Medicine, 2011)