The epidemiology of walking for physical activity in the United StatesEYLER, Amy A; BROWNSON, Ross C; BACAK, Stephen J et al.Medicine and science in sports and exercise. 2003, Vol 35, Num 9, pp 1529-1536, issn 0195-9131, 8 p.Article

Environmental and policy determinants of physical activity in the United StatesBROWNSON, Ross C; BAKER, Elizabeth A; HOUSEMANN, Robyn A et al.American journal of public health (1971). 2001, Vol 91, Num 12, pp 1995-2003, issn 0090-0036Article