diff --git a/.gitignore b/.gitignore
index ac1e8f7..0335b99 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
-node_modules
-*.log
-.DS_Store
+node_modules		 node_modules
+ *.log		 *.log
+ .DS_Store
+ 
\ No newline at end of file
diff --git a/C#/DoubleLinked.cs b/C#/DoubleLinked.cs
new file mode 100644
index 0000000..37e0b96
--- /dev/null
+++ b/C#/DoubleLinked.cs
@@ -0,0 +1,90 @@
+using System;
+
+namespace HowProgrammingWorks.CS.DoubleLinkedList
+{
+    class DoubleLinkedList<T>
+    {
+
+        public int Length { get; private set; }
+
+        public Node<T> First { get; private set; }
+
+        public Node<T> Last { get; private set; }
+
+        public Node<T> Push(T data)
+        {
+            var node = new Node<T>(this, data);
+            node.Previous = this.Last;
+
+            if (this.Length == 0) 
+                this.First = node;
+            else 
+                this.Last.Next = node;
+
+            this.Last = node;
+            this.Length++;
+
+            return node;
+        }
+
+        public T Pop()
+        {
+            if (this.Length == 0)
+                return default(T);
+
+            var node = this.Last;
+
+            this.Length--;
+            this.Last = node.Previous;
+
+            node.List = null;
+            node.Previous = null;
+            node.Next = null;
+            
+            return node.Data;
+        }
+
+    }
+
+    class Node<T>
+    {
+        public DoubleLinkedList<T> List { get; set; }
+        public Node<T> Previous { get; set; }
+        public Node<T> Next { get; set; }
+        public T Data { get; set; }
+
+        public Node(DoubleLinkedList<T> list, T data)
+            : this(list, null, null, data)
+        {
+        }
+
+        protected Node(DoubleLinkedList<T> list, Node<T> previous, Node<T> next, T data)
+        {
+            List = List;
+            Data = data;
+            Next = next;
+            Previous = previous;
+        }
+    }
+
+    public class Example
+    {
+        public void Run()
+        {
+            var list = new DoubleLinkedList<string>();
+
+            list.Push("road");
+            list.Push("the");
+            list.Push("across");
+            list.Push("running");
+            list.Push("was");
+            list.Push("cat");
+            list.Push("Black");
+
+            while (list.Length > 0)
+                Console.Write($"{list.Pop()} ");
+
+            Console.WriteLine();
+        }
+    }
+}
diff --git a/C#/HowProgrammingWorks.CS.csproj b/C#/HowProgrammingWorks.CS.csproj
new file mode 100644
index 0000000..0c14923
--- /dev/null
+++ b/C#/HowProgrammingWorks.CS.csproj
@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <RootNamespace>HowProgrammingWorks.CS</RootNamespace>
+  </PropertyGroup>
+
+</Project>
diff --git a/C#/Program.cs b/C#/Program.cs
new file mode 100644
index 0000000..08b6fa5
--- /dev/null
+++ b/C#/Program.cs
@@ -0,0 +1,20 @@
+using System;
+
+namespace HowProgrammingWorks.CS
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.Clear();
+
+            Console.WriteLine("Linked list");
+            new SingleLinkedList.Example().Run();
+            Console.WriteLine();
+
+            Console.WriteLine("Double linked list");
+            new DoubleLinkedList.Example().Run();
+            Console.WriteLine();
+        }
+    }
+}
diff --git a/C#/SingleLinked.cs b/C#/SingleLinked.cs
new file mode 100644
index 0000000..5b6b5c8
--- /dev/null
+++ b/C#/SingleLinked.cs
@@ -0,0 +1,50 @@
+using System;
+
+namespace HowProgrammingWorks.CS.SingleLinkedList
+{
+    class Node<T>
+    {
+        public Node(T data)
+            :  this(null, data)
+        {            
+        }
+
+        public Node(Node<T> next, T data)
+        {
+            Next = next;
+            Data = data;
+        }
+
+        public Node()
+            : this(null, default(T))
+        {
+        }
+
+        public Node<T> Next { get; set; }
+        public T Data { get; set; }
+    }
+
+    class Example
+    {
+        public void Run()
+        {
+            var n6 = new Node<string>("road");
+            var n5 = new Node<string>(n6, "the");
+            var n4 = new Node<string>(n5, "across");
+            var n3 = new Node<string>(n4, "running");
+            var n2 = new Node<string>(n3, "was");
+            var n1 = new Node<string>(n2, "cat");
+            var n0 = new Node<string>(n1, "Black");
+
+            var currentNode = n0;
+            
+            while (currentNode != null)
+            {
+                Console.Write($"{currentNode.Data} ");
+                currentNode = currentNode.Next;
+            }
+
+            Console.WriteLine();
+        }
+    }
+}
diff --git a/F#/DoubleLinked.fs b/F#/DoubleLinked.fs
new file mode 100644
index 0000000..5732bb7
--- /dev/null
+++ b/F#/DoubleLinked.fs
@@ -0,0 +1,84 @@
+module HowProgrammingWorks.FS.DoubleLinked
+
+open System
+
+type Node<'T> = {
+    mutable prev : Node<'T> option;
+    mutable next : Node<'T> option;
+    mutable data : 'T;
+}
+
+type LinkedList<'T> = {
+    mutable first : Node<'T> option;
+    mutable last : Node<'T> option;
+    mutable count: int;
+}
+
+let push (list : LinkedList<'T>, data: 'T) : Node<'T> =
+    match list.count with
+        | 0 ->
+            let node =  {prev = None; next = None; data = data; }
+            list.first <- Some node;
+            list.last <- Some node;
+            list.count <- list.count + 1;
+            
+            node
+        | _ ->             
+            let node =  {prev = list.last; next = None; data = data; }            
+            list.last.Value.next <- Some node
+            list.last <- Some node
+            list.count <- list.count + 1
+            node
+
+
+let pull (list : LinkedList<'T>) : 'T option =
+    match list.count with
+        | 0 ->
+            None;
+        | 1 ->    
+            let node = list.last.Value;
+            list.last <- None;
+            list.first <- None;
+            list.count <- 0;
+            Some node.data;
+        |_->
+            let node = list.last.Value;
+            list.last <- node.prev;
+            list.count <- list.count - 1;
+            Some node.data;
+
+let pullFromStart (list : LinkedList<'T>) : 'T option =
+    match list.count with
+        | 0 ->
+            None;
+        | 1 ->    
+            let node = list.first.Value;
+            list.last <- None;
+            list.first <- None;
+            list.count <- 0;
+            Some node.data;
+        |_->
+            let node = list.first.Value;
+            list.first <- node.next;
+            list.count <- list.count - 1;
+            Some node.data;
+
+
+let Example =
+
+    let rec write (list : LinkedList<string>) =
+        match list.count with
+            | 0 -> 
+                Console.WriteLine()
+            | _ ->                
+                let value = pullFromStart list; //let value = pull list;
+                printf "%s " value.Value
+                write(list)
+
+    let list : LinkedList<string> = {first = None; last = None; count = 0;}
+
+    let words = [ "Black"; "cat"; "was"; "running"; "across"; "the"; "road"; ]
+    words |> List.iter (fun w -> push(list, w) |> ignore )
+    
+    write list
+    
\ No newline at end of file
diff --git a/F#/HowProgrammingWorks.FS.fsproj b/F#/HowProgrammingWorks.FS.fsproj
new file mode 100644
index 0000000..c385491
--- /dev/null
+++ b/F#/HowProgrammingWorks.FS.fsproj
@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <RootNamespace>HowProgrammingWorks</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="SingleLinked.fs" />
+    <Compile Include="DoubleLinked.fs" />
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+
+</Project>
diff --git a/F#/Program.fs b/F#/Program.fs
new file mode 100644
index 0000000..c4c0341
--- /dev/null
+++ b/F#/Program.fs
@@ -0,0 +1,18 @@
+// Learn more about F# at http://fsharp.org
+
+open System
+
+[<EntryPoint>]
+let main argv =
+    Console.Clear()
+    
+    printf "Linked list: \n"
+    HowProgrammingWorks.FS.SingleLinked.Example
+    printf "\n"
+
+    printf "Double linked list: \n"
+    HowProgrammingWorks.FS.DoubleLinked.Example
+    printf "\n"
+
+    0 // return an integer exit code
+    
\ No newline at end of file
diff --git a/F#/SingleLinked.fs b/F#/SingleLinked.fs
new file mode 100644
index 0000000..f1095fb
--- /dev/null
+++ b/F#/SingleLinked.fs
@@ -0,0 +1,35 @@
+module HowProgrammingWorks.FS.SingleLinked
+
+open System
+
+type Node<'T> = {
+    mutable next : Node<'T> option;
+    mutable data : 'T;
+}
+
+let empty() = {next = None; data = None; }
+
+let pust node data =
+    Some { next = node; data = data }
+
+
+let Example =
+
+    let rec write (x : Node<string> option)  =
+        match x with
+            | None -> 
+                Console.WriteLine()
+            | Some n -> 
+                printf "%s " n.data
+                write n.next
+
+    let n6 : Node<string> = {next = None; data = "road";}
+    let n5 : Node<string> = {next = Some n6; data = "the";}
+    let n4 : Node<string> = {next = Some n5; data = "across";}
+    let n3 : Node<string> = {next = Some n4; data = "running";}
+    let n2 : Node<string>= {next = Some n3; data = "was";}
+    let n1 : Node<string>= {next = Some n2; data = "cat";}
+    let n0 : Node<string>= {next = Some n1; data = "Black";}
+
+    write (Some n0)
+    
\ No newline at end of file
diff --git a/JavaScript/1-single-proto.js b/JavaScript/1-single-proto.js
index b9c350c..e839f0d 100644
--- a/JavaScript/1-single-proto.js
+++ b/JavaScript/1-single-proto.js
@@ -1,15 +1,17 @@
 'use strict';
 
-function Node(prev, data) {
-  this.prev = prev;
+function Node(next, data) {
+  this.next = next;
   this.data = data;
 }
 
 // Usage
 
-const n1 = new Node(null, { name: 'first' });
-const n2 = new Node(n1, { name: 'second' });
-const n3 = new Node(n2, { name: 'third' });
+const n3 = new Node(null, { name: 'third' });
+const n2 = new Node(n3, { name: 'second' });
+const n1 = new Node(n2, { name: 'first' });
+
+
 
 console.dir(n1);
 console.dir(n2);
diff --git a/JavaScript/2-single-factory.js b/JavaScript/2-single-factory.js
index ffc4d01..4ff2144 100644
--- a/JavaScript/2-single-factory.js
+++ b/JavaScript/2-single-factory.js
@@ -1,12 +1,14 @@
 'use strict';
 
-const node = (prev, data) => ({ prev, data });
+const node = (next, data) => ({ next, data });
 
 // Usage
 
-const n1 = node(null, { name: 'first' });
-const n2 = node(n1, { name: 'second' });
-const n3 = node(n2, { name: 'third' });
+const n3 = node(null, { name: 'third' });
+const n2 = node(n3, { name: 'second' });
+const n1 = node(n2, { name: 'first' });
+
+
 
 console.dir(n1);
 console.dir(n2);