Index: doc/bibliography/cfa.bib
===================================================================
--- doc/bibliography/cfa.bib	(revision 06cf47f98c44efe16711356633dcb88ab7b8e699)
+++ doc/bibliography/cfa.bib	(revision ee89ad4324c98026a0307d32744ebff7f615bf34)
@@ -2719,4 +2719,13 @@
 	implementations are the same.
     }
+}
+
+@online{GCCExtensions,
+    contributer = {a3moss@uwaterloo.ca},
+    key = {{GNU}},
+    title = {Extensions to the {C} Language Family},
+    year = 2014,
+    url = {https://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/C-Extensions.html},
+    urldate = {2017-04-02}
 }