diff --git a/Number_types/doc/Number_types/CGAL/Rational_traits.h b/Number_types/doc/Number_types/CGAL/Rational_traits.h
index e35c63e2094..afc5cac4b1b 100644
--- a/Number_types/doc/Number_types/CGAL/Rational_traits.h
+++ b/Number_types/doc/Number_types/CGAL/Rational_traits.h
@@ -36,6 +36,16 @@ returns the denominator of `r`.
 */ 
 RT denominator (const NT & r) const; 
 
+/*! 
+returns self.
+*/ 
+NT make_rational(const NT & x) const; 
+
+/*! 
+constructs a rational number `p.first/p.second`. 
+*/ 
+NT make_rational(const std::pair<RT,RT> & p) const; 
+
 /*! 
 constructs a rational number. 
 */