diff --git a/arch/ia64/lib/idiv32.S b/arch/ia64/lib/idiv32.S
index 2ac28bf0a662d8026c65feb06193b6a3589e4ecf..c91b5b0129ff929e072c80a06e146c529ce18192 100644
--- a/arch/ia64/lib/idiv32.S
+++ b/arch/ia64/lib/idiv32.S
@@ -11,7 +11,7 @@
  *
  * For more details on the theory behind these algorithms, see "IA-64
  * and Elementary Functions" by Peter Markstein; HP Professional Books
- * (http://www.hp.com/go/retailbooks/)
+ * (http://www.goodreads.com/book/show/2019887.Ia_64_and_Elementary_Functions)
  */
 
 #include <asm/asmmacro.h>
diff --git a/arch/ia64/lib/idiv64.S b/arch/ia64/lib/idiv64.S
index f69bd2b0987ac63789b82a6447384ac0b2252c41..627573c4ceb1972c248eeb6ec881f85f1b79ded2 100644
--- a/arch/ia64/lib/idiv64.S
+++ b/arch/ia64/lib/idiv64.S
@@ -11,7 +11,7 @@
  *
  * For more details on the theory behind these algorithms, see "IA-64
  * and Elementary Functions" by Peter Markstein; HP Professional Books
- * (http://www.hp.com/go/retailbooks/)
+ * (http://www.goodreads.com/book/show/2019887.Ia_64_and_Elementary_Functions)
  */
 
 #include <asm/asmmacro.h>