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diff --git a/monster/demon/imp.clsc.LICENSE b/monster/demon/imp.clsc.LICENSE
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--- a/monster/demon/imp.clsc.LICENSE
+++ b/monster/demon/imp.clsc.LICENSE
@@ -1,3 +1,5 @@
-comment Derived from original Crossfire XPM images. Unknown source, but predates CVS repo date of March 1999.
-license unknown
-sourcename Crossfire XPM
+comment Original artwork by David Gervais. Most of this set was used in the Angband project, and uploaded to OpenGameArt. Modified for use with CF.
+license cc-by-3.0
+licenseurl https://creativecommons.org/licenses/by/3.0/legalcode
+sourcename David Gervais
+sourceurl http://pousse.rapiere.free.fr/tome/