diff --git a/Instructor's notes.md b/Instructor's notes.md
index 573a8fe..0114097 100644
--- a/Instructor's notes.md	
+++ b/Instructor's notes.md	
@@ -2,13 +2,13 @@
 
 - #### history_of_linux:
 
-  Most of information are taken from "Introduction to Linux" and "Linux bible" books , GNU documentations, Linus Torvalds posts on comp.os.minix (which are gathered from  https://www.cs.cmu.edu/~awb/linux.history.html) and Wikipedia.
+  Most of information are taken from "Introduction to Linux" and "Linux bible" books , GNU documentations, Linus Torvalds posts on comp.os.minix (which are gathered from [link](https://www.cs.cmu.edu/~awb/linux.history.html) and Wikipedia.
 
   
 
 - #### distributions:
 
-  Most of information are gathered from each distribution own website and https://www.makeuseof.com/tag/whats-the-difference-between-linux-distributions-if-theyre-all-linux-makeuseof-explains/
+  Most of information are gathered from each distribution own website and [link](https://www.makeuseof.com/tag/whats-the-difference-between-linux-distributions-if-theyre-all-linux-makeuseof-explains/)
 
   
 
@@ -20,16 +20,24 @@
 
 - #### linux_file_system
 
-  Most of information are taken from "Introduction to Linux" and "Linux bible" books and following sites: https://www.linuxnix.com/linux-directory-structure-explained-boot-folder/ 
+  Most of information are taken from "Introduction to Linux" and "Linux bible" books and following sites: 
+  
+  [first site](https://www.linuxnix.com/linux-directory-structure-explained-boot-folder/)
 
-  https://opensource.com/life/16/10/introduction-linux-filesystems
+  [second site](https://opensource.com/life/16/10/introduction-linux-filesystems)
   
+  [third site](https://www.howtogeek.com/117435/htg-explains-the-linux-directory-structure-explained/)
+
+  [fourth site](https://opensource.com/life/16/10/introduction-linux-filesystems)
+  
+  [fifth site](https://www.geeksforgeeks.org/linux-directory-structure)
+
   
   
 - ### shell commands
 
     - grep:
-    https://www.cyberciti.biz/faq/howto-use-grep-command-in-linux-unix/
+    [click here](https://www.cyberciti.biz/faq/howto-use-grep-command-in-linux-unix/)
     ps -x | grep firefox
     grep names.csv shayan
     ls -l | grep ^d
@@ -42,7 +50,7 @@
     ls -l > test.o
     sed -ni 's/Desktop/Dekstop/gi'
     sed /^%/d' file.txt
-    https://www.digitalocean.com/community/tutorials/the-basics-of-using-the-sed-stream-editor-to-manipulate-text-in-linux#printing-lines
+    [click here](https://www.digitalocean.com/community/tutorials/the-basics-of-using-the-sed-stream-editor-to-manipulate-text-in-linux#printing-lines)
     
     - how to fuck your system nicely
     create a infinite loop in a programming language
@@ -58,5 +66,16 @@
     echo main.o >> .gitignore
 
 
-
+- ### systemd
+  almost all of the information for systemd are taken from the following webistes:
+  
+  - [first](https://www.linux-magazine.com/Issues/2017/200/Tutorials-Systemd#article_f1)
+  
+  - [second](https://en.wikipedia.org/wiki/Systemd)
+  
+  - [third](https://www.freedesktop.org/wiki/Software/systemd/)
+  
+  - [fourth](https://www.linux.com/training-tutorials/understanding-and-using-systemd/)
+  
+  - [fifth](https://www.tutorialspoint.com/linux_admin/linux_admin_systemd_services_start_and_stop.htm)
 
diff --git a/PowerPoint/introduction-to-systemd.pptx b/PowerPoint/introduction-to-systemd.pptx
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diff --git a/PowerPoint/linux-fest-directory.pptx b/PowerPoint/linux-fest-directory.pptx
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diff --git a/README.md b/README.md
index 56aea32..3806614 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,6 @@
+<div align="center">
+  <h1> In The Name of GOD </h1>
+</div>
+
 # introduction_to_linux
+  This repository contains useful information about the presentation materials for Amirkabir Univesity of Technology(AUT)