diff --git a/build.ln b/build.ln
index afa2528..2a0641a 100644
--- a/build.ln
+++ b/build.ln
@@ -3,7 +3,7 @@
         "dotnet"
     ],
     "env": {
-        "NUGET_SOURCE": "https://nexus.niclas-thobaben.de/repository/l--n.de/",
+        "NUGET_SOURCE": "https://nexus.l--n.de/repository/ln.net/",
         "CONFIGURATION": "Release"
     },
     "stages": [
diff --git a/ln.collections.test/ln.collections.test.csproj b/ln.collections.test/ln.collections.test.csproj
index c64a042..d363dd0 100644
--- a/ln.collections.test/ln.collections.test.csproj
+++ b/ln.collections.test/ln.collections.test.csproj
@@ -4,7 +4,7 @@
 
     <IsPackable>false</IsPackable>
 
-    <TargetFrameworks>net5.0;netcoreapp3.1</TargetFrameworks>
+    <TargetFrameworks>net5.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/ln.collections/BTree.cs b/ln.collections/BTree.cs
index ae613f2..ca535eb 100644
--- a/ln.collections/BTree.cs
+++ b/ln.collections/BTree.cs
@@ -4,7 +4,7 @@ using System.Collections.Generic;
 using System.Linq;
 namespace ln.collections
 {
-    public class BTree<K,V> : IDict<K,V>
+    public class BTree<K,V> : IDict<K,V>, IEnumerable<KeyValuePair<K,V>>
     {
         public Comparison<K> Comparison { get; }
         public int Count => count;
@@ -629,6 +629,22 @@ namespace ln.collections
         IEnumerable IDict.Keys => Keys;
         IEnumerable IDict.Values => Values;
 
+        public IEnumerable<KeyValuePair<K, V>> GetInterval(K start, K end) => GetInterval(start, end, null);
+
+        public IEnumerable<KeyValuePair<K, V>> GetInterval(K start, K end, Func<K,V,bool> filter)
+        {
+            TreeNode currentNode = (start is null) ? First(headNode) : FindFirstGE(start);
+            if (currentNode != null)
+            {
+                while ((currentNode is not null) && ((end is null) || (Comparison(currentNode.Key, end) <=  0)))
+                {
+                    if (filter is null || filter(currentNode.Key, currentNode.Value))
+                        yield return new KeyValuePair<K, V>(currentNode.Key, currentNode.Value);
+                    currentNode = Next(currentNode);
+                }
+            }
+        }
+
         class TreeNode
         {
             public BTree<K, V> Tree { get; }
@@ -720,6 +736,20 @@ namespace ln.collections
 
         }
 
+        public IEnumerator<KeyValuePair<K, V>> GetEnumerator()
+        {
+            TreeNode node = First(headNode);
+            while (node != null)
+            {
+                yield return new KeyValuePair<K, V>(node.Key, node.Value);
+                node = Next(node);
+            }
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
     }
 
     public class BTree<K> : BTree<K,object>
diff --git a/ln.collections/BTreeValueList.cs b/ln.collections/BTreeValueList.cs
index f13da40..3c77924 100644
--- a/ln.collections/BTreeValueList.cs
+++ b/ln.collections/BTreeValueList.cs
@@ -1,9 +1,10 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 namespace ln.collections
 {
-    public class BTreeValueList<K, V>
+    public class BTreeValueList<K, V> : IEnumerable<KeyValuePair<K,V>>
     {
         public bool Empty => bTree.Empty;
 
@@ -143,15 +144,16 @@ namespace ln.collections
         public IEnumerable<K> Keys => bTree.Keys;
         public IEnumerable<V> Values => bTree.Values.SelectMany(vl => vl);
 
-        public IEnumerable<KeyValuePair<K, V>> GetKeyValuePairs()
+        public IEnumerator<KeyValuePair<K, V>> GetEnumerator()
         {
-            foreach (K key in Keys)
+            foreach (KeyValuePair<K, List<V>> vl in this.bTree)
+            foreach (V v in vl.Value)
             {
-                List<V> lv = bTree[key];
-                foreach (V value in lv)
-                    yield return new KeyValuePair<K, V>(key, value);
+                yield return new KeyValuePair<K, V>(vl.Key, v);
             }
         }
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
         public void AddRange(IEnumerable<KeyValuePair<K, V>> keyValuePairs)
         {
             foreach (KeyValuePair<K, V> keyValuePair in keyValuePairs)
diff --git a/ln.collections/BTreeValueSet.cs b/ln.collections/BTreeValueSet.cs
index 4140f13..f240e9d 100644
--- a/ln.collections/BTreeValueSet.cs
+++ b/ln.collections/BTreeValueSet.cs
@@ -1,11 +1,14 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
+
 namespace ln.collections
 {
-    public class BTreeValueSet<K, V>
+    public class BTreeValueSet<K, V> : IEnumerable<KeyValuePair<K, V>>
     {
         public bool Empty => bTree.Empty;
+        public Comparison<K> Comparison => bTree.Comparison;
 
         BTree<K, HashSet<V>> bTree;
 
@@ -13,6 +16,7 @@ namespace ln.collections
         {
             bTree = new BTree<K, HashSet<V>>();
         }
+
         public BTreeValueSet(Comparison<K> comparison)
         {
             bTree = new BTree<K, HashSet<V>>(comparison);
@@ -22,10 +26,11 @@ namespace ln.collections
         {
             get
             {
-                if (TryGet(key,out IEnumerable<V> values))
+                if (TryGet(key, out IEnumerable<V> values))
                 {
                     return values;
                 }
+
                 throw new KeyNotFoundException();
             }
         }
@@ -35,41 +40,48 @@ namespace ln.collections
             if (!TryAdd(key, value))
                 throw new ArgumentException("duplicate key");
         }
+
         public void Remove(K key, V value)
         {
             if (!TryRemove(key, value))
                 throw new KeyNotFoundException();
         }
+
         public void Remove(K key)
         {
             if (!TryRemove(key))
                 throw new KeyNotFoundException();
         }
 
-        public bool TryAdd(K key,V value)
+        public bool TryAdd(K key, V value)
         {
             if (!bTree.TryGet(key, out HashSet<V> values))
             {
                 values = new HashSet<V>();
                 bTree.Add(key, values);
             }
+
             return values.Add(value);
         }
-        public bool TryGet(K key,out IEnumerable<V> values)
+
+        public bool TryGet(K key, out IEnumerable<V> values)
         {
             if ((!bTree.TryGet(key, out HashSet<V> v)) || (v.Count == 0))
             {
                 values = v;
                 return false;
             }
+
             values = v;
             return true;
         }
+
         public bool TryRemove(K key)
         {
             return bTree.TryRemove(key);
         }
-        public bool TryRemove(K key,V value)
+
+        public bool TryRemove(K key, V value)
         {
             if (bTree.TryGet(key, out HashSet<V> values))
             {
@@ -78,14 +90,17 @@ namespace ln.collections
                     bTree.Remove(key);
                 return success;
             }
+
             return false;
         }
+
         public bool ContainsKey(K key)
         {
             if (!bTree.TryGet(key, out HashSet<V> _values))
                 return false;
             return _values.Count > 0;
         }
+
         public bool ContainsValue(V value)
         {
             foreach (HashSet<V> _values in bTree.Values)
@@ -94,6 +109,7 @@ namespace ln.collections
                     if (v.Equals(value))
                         return true;
             }
+
             return false;
         }
 
@@ -104,17 +120,17 @@ namespace ln.collections
             return _values.Count;
         }
 
-		public void Clear()
-		{
-			bTree.Clear();
-		}
+        public void Clear()
+        {
+            bTree.Clear();
+        }
 
         public K First => bTree.First();
         public K Last => bTree.Last();
 
         public IEnumerable<K> Keys => bTree.Keys;
-        public IEnumerable<V> Values => bTree.Values.SelectMany(vl => vl);
-
+        public IEnumerable<V> Values => bTree.Values.SelectMany(vl => vl);
+
         public IEnumerable<KeyValuePair<K, V>> GetKeyValuePairs()
         {
             foreach (K key in Keys)
@@ -124,11 +140,36 @@ namespace ln.collections
                     yield return new KeyValuePair<K, V>(key, value);
             }
         }
+
         public void AddRange(IEnumerable<KeyValuePair<K, V>> keyValuePairs)
         {
             foreach (KeyValuePair<K, V> keyValuePair in keyValuePairs)
                 Add(keyValuePair.Key, keyValuePair.Value);
         }
 
+        public IEnumerable<KeyValuePair<K, V>> GetInterval(K start, K end) => GetInterval(start, end, null);
+        public IEnumerable<KeyValuePair<K, V>> GetInterval(K start, K end, Func<K,V,bool> filter)
+        {
+            foreach (KeyValuePair<K, HashSet<V>> vl in this.bTree.GetInterval(start, end))
+            foreach (V v in vl.Value)
+            {
+                if (filter is null || filter(vl.Key, v))
+                    yield return new KeyValuePair<K, V>(vl.Key, v);
+            }
+        }
+
+        public IEnumerator<KeyValuePair<K, V>> GetEnumerator()
+        {
+            foreach (KeyValuePair<K, HashSet<V>> vl in this.bTree)
+            foreach (V v in vl.Value)
+            {
+                    yield return new KeyValuePair<K, V>(vl.Key, v);
+            }
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
     }
 }
diff --git a/ln.collections/ln.collections.csproj b/ln.collections/ln.collections.csproj
index 7c9ac1c..086d267 100644
--- a/ln.collections/ln.collections.csproj
+++ b/ln.collections/ln.collections.csproj
@@ -2,13 +2,13 @@
 
     <PropertyGroup>
         <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-        <Version>0.1.5</Version>
+        <Version>0.1.6</Version>
         <Authors>Harald Wolff-Thobaben</Authors>
         <Company>l--n.de</Company>
         <AssemblyVersion>0.0.1.1</AssemblyVersion>
         <FileVersion>0.0.1.1</FileVersion>
-        <PackageVersion>0.1.5</PackageVersion>
-        <TargetFrameworks>net5.0;netcoreapp3.1</TargetFrameworks>
+        <PackageVersion>0.1.7</PackageVersion>
+        <TargetFramework>net5.0</TargetFramework>
     </PropertyGroup>
 
     <ItemGroup>