diff --git a/passes/techmap/abc9.cc b/passes/techmap/abc9.cc
index 17a5c0fe3..30cd68881 100644
--- a/passes/techmap/abc9.cc
+++ b/passes/techmap/abc9.cc
@@ -22,14 +22,6 @@
 // Berkeley Logic Synthesis and Verification Group, ABC: A System for Sequential Synthesis and Verification
 // http://www.eecs.berkeley.edu/~alanmi/abc/
 
-// [[CITE]] Berkeley Logic Interchange Format (BLIF)
-// University of California. Berkeley. July 28, 1992
-// http://www.ece.cmu.edu/~ee760/760docs/blif.pdf
-
-// [[CITE]] Kahn's Topological sorting algorithm
-// Kahn, Arthur B. (1962), "Topological sorting of large networks", Communications of the ACM 5 (11): 558-562, doi:10.1145/368996.369025
-// http://en.wikipedia.org/wiki/Topological_sorting
-
 #define ABC_COMMAND_LIB "strash; ifraig; scorr; dc2; dretime; strash; &get -n; &dch -f; &nf {D}; &put"
 #define ABC_COMMAND_CTR "strash; ifraig; scorr; dc2; dretime; strash; &get -n; &dch -f; &nf {D}; &put; buffer; upsize {D}; dnsize {D}; stime -p"
 //#define ABC_COMMAND_LUT "strash; ifraig; scorr; dc2; dretime; strash; dch -f; if; mfs2"