Dewulf, B., Neutens, T., Van Dyck, D., De Bourdeaudhuij, I., Broekx, S., Beckx, C. and Van de Weghe, N. (2016) “Associations between time spent in green areas and physical activity among late middle-aged adults”, Geospatial Health, 11(3). doi: 10.4081/gh.2016.411.