diff --git a/DesignPatternsSolution/Execise.Tests/Execise.Tests.csproj b/DesignPatternsSolution/Execise.Tests/Execise.Tests.csproj
index 71e68ac..4f78f0d 100644
--- a/DesignPatternsSolution/Execise.Tests/Execise.Tests.csproj
+++ b/DesignPatternsSolution/Execise.Tests/Execise.Tests.csproj
@@ -8,7 +8,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>Execise.Tests</RootNamespace>
     <AssemblyName>Execise.Tests</AssemblyName>
-    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <ProjectTypeGuids>{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">10.0</VisualStudioVersion>
@@ -16,6 +16,7 @@
     <ReferencePath>$(ProgramFiles)\Common Files\microsoft shared\VSTT\$(VisualStudioVersion)\UITestExtensionPackages</ReferencePath>
     <IsCodedUITest>False</IsCodedUITest>
     <TestProjectType>UnitTest</TestProjectType>
+    <TargetFrameworkProfile />
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
diff --git a/DesignPatternsSolution/Execise.Tests/UnitTests.cs b/DesignPatternsSolution/Execise.Tests/UnitTests.cs
index 0a3b80e..23a006e 100644
--- a/DesignPatternsSolution/Execise.Tests/UnitTests.cs
+++ b/DesignPatternsSolution/Execise.Tests/UnitTests.cs
@@ -1,4 +1,5 @@
-using Exercise;
+using System;
+using Exercise;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 namespace Execise.Tests
@@ -12,18 +13,27 @@ public void LibraryShouldBeSingleton()
         {
             //check that when you create a Library instance second time, 
             //you get exactly the same instance as for a very first time
+            var a = Library.getLibInstance();
+            var b = Library.getLibInstance();
+            var bSameObject = ReferenceEquals(a, b);
+            Assert.AreEqual(true, bSameObject, "Objects returned are different");
         }
 
         //test that an book was registered successfully by checking the returned Id value is not -1
         [TestMethod]
         public void BookShouldRegister()
         {
+            var registeredId = RegistrationRepository.Register(new Book("bill", "bill's book", 1995, 5));
+            Assert.AreNotEqual(-1, registeredId);  
+
         }
 
         //test that an customer was registered successfully by checking the returned Id value is not -1
         [TestMethod]
         public void CustomerShouldRegister()
         {
+            var registeredId = RegistrationRepository.Register(new Customer("bill", "bill's addr"));
+            Assert.AreNotEqual(-1, registeredId);  
         }
 
         //test that a book can be borrowed
diff --git a/DesignPatternsSolution/Exercise/Exercise.csproj b/DesignPatternsSolution/Exercise/Exercise.csproj
index d2cc582..87a49ae 100644
--- a/DesignPatternsSolution/Exercise/Exercise.csproj
+++ b/DesignPatternsSolution/Exercise/Exercise.csproj
@@ -9,9 +9,10 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>Exercise</RootNamespace>
     <AssemblyName>Exercise</AssemblyName>
-    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
+    <TargetFrameworkProfile />
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
diff --git a/DesignPatternsSolution/Exercise/Item.cs b/DesignPatternsSolution/Exercise/Item.cs
index 92c21e1..be87921 100644
--- a/DesignPatternsSolution/Exercise/Item.cs
+++ b/DesignPatternsSolution/Exercise/Item.cs
@@ -10,7 +10,7 @@ public Item(int amount, int year)
         }
     }
 
-    public class Book : Item
+    public class Book : Item, IRegistarable
     {
         public Book(string author, string title, int year, int amount) : base(amount, year)
         {
@@ -18,5 +18,34 @@ public Book(string author, string title, int year, int amount) : base(amount, ye
             Author = author;
         }
         public string Author { get; set; }
+
+        public RegisteredObject GetRegistrationInfo()
+        {
+            return new RegisteredObject()
+            {
+                AvailableAmount = AvailableAmount,
+                Info = NameOrTitle
+            };
+        }
+    }
+
+    public class Video : Item, IRegistarable
+    {
+        public Video(string director, string title, int year, int amount)
+            : base(amount, year)
+        {
+            NameOrTitle = title;
+            Director = director;
+        }
+        public string Director { get; set; }
+        
+        public RegisteredObject GetRegistrationInfo()
+        {
+            return new RegisteredObject()
+            {
+                AvailableAmount = AvailableAmount,
+                Info = NameOrTitle
+            };
+        }
     }
 }
diff --git a/DesignPatternsSolution/Exercise/Library.cs b/DesignPatternsSolution/Exercise/Library.cs
index 1d9dde4..cc175f8 100644
--- a/DesignPatternsSolution/Exercise/Library.cs
+++ b/DesignPatternsSolution/Exercise/Library.cs
@@ -1,18 +1,26 @@
-namespace Exercise
+using System.Runtime.Remoting.Messaging;
+
+namespace Exercise
 {
     public class Library
     {
         //implement Singleton to make sure only one library will exist
+        private static Library libInstance = new Library();
 
-        
+        private Library()
+        {
+        }
 
-        //Implement Register method by utilizing RegistrationRepository (complete missing parts)
-        public int Register()
+        public static Library getLibInstance()
         {
-            // return RegistrationRepository.Register();
+            return libInstance;
+        }
+
 
-            //dummy, just to compile
-            return 0;
+        //Implement Register method by utilizing RegistrationRepository (complete missing parts)
+        public int Register(IRegistarable libObject)
+        {
+            return RegistrationRepository.Register(libObject);
         }
     }
 }
diff --git a/DesignPatternsSolution/Exercise/Person.cs b/DesignPatternsSolution/Exercise/Person.cs
index 2c2ed21..e1cc4cb 100644
--- a/DesignPatternsSolution/Exercise/Person.cs
+++ b/DesignPatternsSolution/Exercise/Person.cs
@@ -2,7 +2,7 @@
 
 namespace Exercise
 {
-    public class Customer : LibObject
+    public class Customer : LibObject, IRegistarable
     {
         public string Address { get; set; }
         public DateTime RegisteredAt { get; set; }
@@ -19,5 +19,14 @@ public void SetId(int id)
         {
             ObjectId = id;
         }
+
+        public RegisteredObject GetRegistrationInfo()
+        {
+            return new RegisteredObject()
+            {
+                AvailableAmount = 1,
+                Info = NameOrTitle
+            };
+        }
     }
 }