diff --git a/004.copper_bars/README.md b/004.copper_bars/README.md
index f791a1a..b77e15d 100644
--- a/004.copper_bars/README.md
+++ b/004.copper_bars/README.md
@@ -7,6 +7,6 @@ Some notes:
   1. The first line is copper address $2c
   2. The last last is copper address $2c + 256 (screen height) = $12c
 
-At copper line 255 ($FF), we run out of bits in the copper wait instruction, so if we want to wait for lines after this, we need to wait for a wrapped value. [See here](http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node004D.html)
+At copper line 255 ($FF), we run out of bits in the copper wait instruction, so if we want to wait for lines after this, we need to wait for a wrapped value. [See hardware reference manual details here](http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node004D.html)
 
 [copper_gen.c](copper_gen.c) will generate a copper list with horizontal bars. See http://krazydad.com/tutorials/makecolors.php for details on the algorithm used to generate the bars.  You can generate all sorts of different kinds of patterns by changing the algorithm parameters.