sources/bitmap/sources.txt

   1 Soil texture:
   2 https://commons.wikimedia.org/wiki/File:2008-08-12_Mulch.jpg
   3
   4 Stone texture:
   5 https://commons.wikimedia.org/wiki/File:Galets.jpg
   6
   7 Shrub texture:
   8 https://commons.wikimedia.org/wiki/File:Gew%C3%B6hnlicher_Buchsbaum,_Buxus_sempervirens_.JPG