Reference

Venter O, Sanderson EW, Magrach A, Allan JR, Beher J, Jones KR, Possingham HP, Laurance WF, Wood P, Fekete BM, Levy MA & Watson JEM (2016a). Global terrestrial human footprint maps for 1993 and 2009. Scientific Data 3(1):160067.
Venter O, Sanderson EW, Magrach A, Allan JR, Beher J, Jones KR, Possingham HP, Laurance WF, Wood P, Fekete BM, Levy MA & Watson JEM (2016b). Sixteen years of change in the global terrestrial human footprint and implications for biodiversity conservation. Nature Communications 7(1):12558.