Multiple quad8 changes

Change-Id: Ia9f2b1550c7d7d4364fcb9fb91a5e41ff6778cc7
diff --git a/quad8/continuummechanics/homework/hw6/references.bib b/quad8/continuummechanics/homework/hw6/references.bib
new file mode 100644
index 0000000..67fd916
--- /dev/null
+++ b/quad8/continuummechanics/homework/hw6/references.bib
@@ -0,0 +1,4 @@
+@online{se,
+  title={Curl in cylindrical coordinates - StackExchange Mathematics},
+  url={https://math.stackexchange.com/a/2160871}
+}