diff --git a/X10D/src/Collections/DictionaryExtensions.cs b/X10D/src/Collections/DictionaryExtensions.cs
index c016654..fe0db27 100644
--- a/X10D/src/Collections/DictionaryExtensions.cs
+++ b/X10D/src/Collections/DictionaryExtensions.cs
@@ -1,4 +1,4 @@
-using System.Diagnostics.Contracts;
+using System.Diagnostics.Contracts;
 using System.Web;
 
 namespace X10D.Collections;
@@ -180,6 +180,7 @@ public static class DictionaryExtensions
     /// <typeparam name="TValue">The type of the value element of the key/value pair.</typeparam>
     /// <param name="source">The source dictionary.</param>
     /// <returns>A <see cref="string" /> representing the dictionary as a key=value set, concatenated with <c>;</c>.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="source" /> is <see langword="null" />.</exception>
     [Pure]
     public static string ToConnectionString<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source)
     {
@@ -217,6 +218,11 @@ public static class DictionaryExtensions
     ///     A transform function to apply to the <see cref="KeyValuePair{TKey,TValue}.Value" /> of each element.
     /// </param>
     /// <returns>A <see cref="string" /> representing the dictionary as a key=value set, concatenated with <c>;</c>.</returns>
+    /// <exception cref="ArgumentNullException">
+    ///     <para><paramref name="source" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="selector" /> is <see langword="null" />.</para>
+    /// </exception>
     [Pure]
     public static string ToConnectionString<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source,
         Func<TValue, string?> selector)
@@ -263,6 +269,13 @@ public static class DictionaryExtensions
     ///     A transform function to apply to the <see cref="KeyValuePair{TKey,TValue}.Value" /> of each element.
     /// </param>
     /// <returns>A <see cref="string" /> representing the dictionary as a key=value set, concatenated with <c>;</c>.</returns>
+    /// <exception cref="ArgumentNullException">
+    ///     <para><paramref name="source" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="keySelector" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="valueSelector" /> is <see langword="null" />.</para>
+    /// </exception>
     [Pure]
     public static string ToConnectionString<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source,
         Func<TKey, string> keySelector, Func<TValue, string?> valueSelector)
@@ -308,6 +321,7 @@ public static class DictionaryExtensions
     /// <typeparam name="TValue">The type of the value element of the key/value pair.</typeparam>
     /// <param name="source">The source dictionary.</param>
     /// <returns>A <see cref="string" /> representing the dictionary as a key=value set, concatenated with <c>&amp;</c>.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="source" /> is <see langword="null" />.</exception>
     [Pure]
     public static string ToGetParameters<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source)
         where TKey : notnull
@@ -337,6 +351,11 @@ public static class DictionaryExtensions
     ///     A transform function to apply to the <see cref="KeyValuePair{TKey,TValue}.Value" /> of each element.
     /// </param>
     /// <returns>A <see cref="string" /> representing the dictionary as a key=value set, concatenated with <c>&amp;</c>.</returns>
+    /// <exception cref="ArgumentNullException">
+    ///     <para><paramref name="source" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="selector" /> is <see langword="null" />.</para>
+    /// </exception>
     [Pure]
     public static string ToGetParameters<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source,
         Func<TValue, string?> selector)
@@ -376,6 +395,13 @@ public static class DictionaryExtensions
     ///     A transform function to apply to the <see cref="KeyValuePair{TKey,TValue}.Value" /> of each element.
     /// </param>
     /// <returns>A <see cref="string" /> representing the dictionary as a key=value set, concatenated with <c>&amp;</c>.</returns>
+    /// <exception cref="ArgumentNullException">
+    ///     <para><paramref name="source" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="keySelector" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="valueSelector" /> is <see langword="null" />.</para>
+    /// </exception>
     [Pure]
     public static string ToGetParameters<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source,
         Func<TKey, string> keySelector, Func<TValue, string?> valueSelector)