diff --git a/10_network_and_ssh.Rmd b/10_network_and_ssh.Rmd
index a02c253e5221c33ac8062905393efc1721772898..327645ba9fda17a4f9b7f20c3aba0237e27a0497 100644
--- a/10_network_and_ssh.Rmd
+++ b/10_network_and_ssh.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Learn basics of ssh connection in GNU/Linux
 
diff --git a/11_install_system_programs.Rmd b/11_install_system_programs.Rmd
index df8f514ca44f5997a140f27d6c9667393479bc09..983bb53761b16c07e3d4ef9c95dfeea200fcdb43 100644
--- a/11_install_system_programs.Rmd
+++ b/11_install_system_programs.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Learn how to install programs in GNU/Linux
 
diff --git a/12_virtualization.Rmd b/12_virtualization.Rmd
index 863e14b5f6f5f433c0f451299a772bdd000550e2..935ed75599a8b8f1dc5367bc2f1d3e37b7a8c4f0 100644
--- a/12_virtualization.Rmd
+++ b/12_virtualization.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Learn how to build virtual images or container of a system
 
diff --git a/1_understanding_a_computer.Rmd b/1_understanding_a_computer.Rmd
index 4e706855dba3897f7ec02e0680d17863a8a7c111..3cc49f7ee8d8e35848719eb15e5c7866738c806c 100644
--- a/1_understanding_a_computer.Rmd
+++ b/1_understanding_a_computer.Rmd
@@ -59,7 +59,7 @@ Objective: understand the relations between the different components of a comput
 
 ## As simple as a Turing machine ?
 
-![universal_truing_machine](./img/universal_truing_machine.png){width=100%}
+![Universal Truing Machine](./img/universal_truing_machine.png){width=100%}
 
 - A tape divided into cells, one next to the other. Each cell contains a symbol from some finite alphabet.
 - A head that can read and write symbols on the tape and move the tape left and right one (and only one) cell at a time.
@@ -106,7 +106,7 @@ Disadvantages:
 
 > The kernel provides the most basic level of control over all of the computer's hardware devices. It manages memory access for programs in the RAM, it determines which programs get access to which hardware resources, it sets up or resets the CPU's operating states for optimal operation at all times, and it organizes the data for long-term non-volatile storage with file systems on such media as disks, tapes, flash memory, etc.
 
-[Kernel](./img/220px-Kernel_Layout.svg.png){width=100%}
+![Kernel](./img/220px-Kernel_Layout.svg.png){width=100%}
 
 ---
 
diff --git a/2_using_the_ifb_cloud.Rmd b/2_using_the_ifb_cloud.Rmd
index ebebcca6b195c178b32cc6e5c82eb06bad042a7a..76457c5d3486165d873c53d6e77c6e33e387c0df 100644
--- a/2_using_the_ifb_cloud.Rmd
+++ b/2_using_the_ifb_cloud.Rmd
@@ -16,8 +16,6 @@ knitr::opts_chunk$set(comment = NA)
 <img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
 </a>
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
-
 Objective: Start and connect to an appliance on the IFB cloud
 
 Instead of working on your computer where you don't have an Unix-like OS or have limited right, we are going to use the [IFB (Institut Français de bio-informatique) Cloud]( https://biosphere.france-bioinformatique.fr/).
diff --git a/3_first_steps_in_a_terminal.Rmd b/3_first_steps_in_a_terminal.Rmd
index c543a6adb8515070bd91fdc5e4b87924eb2fd279..a4b7be59922d4a6ca317d9a85de2cd69d9991524 100644
--- a/3_first_steps_in_a_terminal.Rmd
+++ b/3_first_steps_in_a_terminal.Rmd
@@ -16,9 +16,6 @@ knitr::opts_chunk$set(comment = NA)
 <img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
 </a>
 
-
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
-
 Objective: learn to use basic terminal command
 
 Congratulations you are now connected on your VM !
diff --git a/4_unix_file_system.Rmd b/4_unix_file_system.Rmd
index 8dd69526522b24d3e95ebabac21a4aa1ea94bd97..4de19a2e63e27fbd60d09e9c36168519e4cefdde 100644
--- a/4_unix_file_system.Rmd
+++ b/4_unix_file_system.Rmd
@@ -16,8 +16,6 @@ knitr::opts_chunk$set(comment = NA)
 <img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
 </a>
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
-
 Objective: Understand how files are organized in Unix
 
 > On a UNIX system, everything is a file ; if something is not a file, it is a process.
diff --git a/5_users_and_rights.Rmd b/5_users_and_rights.Rmd
index 559b1d65c5754a2524e0906df837404d406b5d9c..c4339b3923ef58a1cda4f0c835f7eb6a7288571b 100644
--- a/5_users_and_rights.Rmd
+++ b/5_users_and_rights.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Understand how rights works in GNU/Linux
 
diff --git a/6_unix_processes.Rmd b/6_unix_processes.Rmd
index 1fabd0646ca02fafaafb5595f3b43fb9e76b60b7..999f9ab7b3ffb2c051355a444f0bea7b73180b9a 100644
--- a/6_unix_processes.Rmd
+++ b/6_unix_processes.Rmd
@@ -12,9 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-## Unix Processes
-
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Understand how process works in GNU/Linux
 
diff --git a/7_streams_and_pipes.Rmd b/7_streams_and_pipes.Rmd
index ad1cac8dcc3ceae55330fe163f82dcd41fe220c6..f86a5ce80edd3769765ab1468e976494d5f618e8 100644
--- a/7_streams_and_pipes.Rmd
+++ b/7_streams_and_pipes.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Understand function of streams and pipes in Unix systems
 
diff --git a/8_text_manipulation.Rmd b/8_text_manipulation.Rmd
index bf297dd16030f1fde5197bcb470761aae96a70ba..08c18ebccbef806964210045543413069a0ced36 100644
--- a/8_text_manipulation.Rmd
+++ b/8_text_manipulation.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Learn simple ways to work with text file in Unix
 
diff --git a/9_batch_processing.Rmd b/9_batch_processing.Rmd
index 92ba7b3bdf58c7aece479492057eee435ef5f45e..5ecaf3a9a6aaa40f250da688cf4fb440cf363eb5 100644
--- a/9_batch_processing.Rmd
+++ b/9_batch_processing.Rmd
@@ -12,7 +12,9 @@ knitr::opts_chunk$set(echo = TRUE)
 knitr::opts_chunk$set(comment = NA)
 ```
 
-[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">
+<img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" />
+</a>
 
 Objective: Learn basics of batch processing in GNU/Linux