diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex
index 46388b2..505ae2e 100644
--- a/Doc/ref/ref3.tex
+++ b/Doc/ref/ref3.tex
@@ -165,7 +165,8 @@
 
 \begin{description}
 \item[Integers]
-These represent elements from the mathematical set of whole numbers.
+These represent elements from the mathematical set of whole numbers
+(positive and negative ones).
 \obindex{integer}
 
 There are three types of integers: