add attribution to README

README

@@ -1,8 +1,19 @@
+Original model by Paul Toxopeus "Large Summer Tree".
+
+LDraw model by Johannes Schauer, released under CC-BY.
+
+The model was made after the images and videos released by Paul Toxopeus:
+
+ - http://www.flickr.com/photos/paultox/sets/72157627230568694/
+ - http://youtu.be/TQJfoQjZ9yU
+
+For a bricklink XML convert the following part IDs:
+
 convert 4460 -> 4460b
 convert 3040b -> 3040
 convert 4032a -> 4032
 
-The following additions were made to the *.pov file:
+The following additions were made to the *.pov file generated by LDView:
 
 	#version 3.6;