diff --git a/src/FSharpAux.Core/ResizeArray.fs b/src/FSharpAux.Core/ResizeArray.fs
index 17c5d2e..3543e70 100644
--- a/src/FSharpAux.Core/ResizeArray.fs
+++ b/src/FSharpAux.Core/ResizeArray.fs
@@ -402,6 +402,9 @@ module ResizeArray =
                 accv <- currv
         accv
 
+/// <summary>Sums all the values in the <paramref name="array"/>.</summary>
+    /// <param name="array">The input ResizeArray.</param>
+    /// <returns>The resulting sum.</returns>   
     let inline sum (array: ResizeArray< ^T>) =
         checkNonNull "array" array
         let mutable acc = LanguagePrimitives.GenericZero< ^T>
@@ -409,6 +412,10 @@ module ResizeArray =
             acc <- Checked.(+) acc array.[i]
         acc
 
+    /// <summary>Returns the sum of the results generated by applying the function (<paramref name="projection"/>) to each element of the <paramref name="array"/>.</summary>
+    /// <param name="projection">The function to transform the ResizeArray elements into the type to be summed.</param>
+    /// <param name="array">The input ResizeArray.</param>
+    /// <returns>The resulting sum.</returns>  
     let inline sumBy ([<InlineIfLambda>] projection: 'T -> ^R) (array: ResizeArray<'T>) =
         checkNonNull "array" array
         let mutable acc = LanguagePrimitives.GenericZero< ^R>
@@ -416,9 +423,13 @@ module ResizeArray =
             acc <- Checked.(+) acc (projection array.[i])
         acc
 
-    let countIf (projection: 'T -> bool) (arr: ResizeArray<'T>): int =  
+    /// <summary>Counts the number of elements in the <paramref name="array"/> satisfying the <paramref name="predicate"/>.</summary>
+    /// <param name="predicate">The function to transform the ResizeArray elements into the type to be summed.</param>
+    /// <param name="array">The input ResizeArray.</param>
+    /// <returns>Number of elements satisfying the <paramref name="predicate"/>.</returns>  
+    let countIf (predicate: 'T -> bool) (arr: ResizeArray<'T>): int =  
         let mutable acc = 0
         for i=0 to arr.Count - 1 do
-            if projection arr.[i] then
+            if predicate arr.[i] then
                 acc <- acc + 1
         acc
\ No newline at end of file