diff --git a/2019-03-01.md b/2019-03-01.md
index 4473b07..cc99301 100644
--- a/2019-03-01.md
+++ b/2019-03-01.md
@@ -81,3 +81,5 @@ antenna_check(gate, metal2, 10.0, diode).output("Antenna ratio metal2/gate > 10"
 # of diode area
 antenna_check(gate, metal2, 10.0, [ diode, 5.0 ]).output("Antenna ratio metal2/gate > 10, each diode increases ratio by 5.0 per square um of diode area")
 ```
+
+For more details see the DRC reference: www.klayout.org/downloads/dvb/doc-qt5/about/drc_ref_global.html