diff --git a/common/modules/source-code-different-long.org b/common/modules/source-code-different-long.org
index 54a5176..5fe1589 100644
--- a/common/modules/source-code-different-long.org
+++ b/common/modules/source-code-different-long.org
@@ -1,106 +1,106 @@
 #+COLUMNS: %40ITEM %10BEAMER_env(Env) %9BEAMER_envargs(Env Args) %10BEAMER_act(Act) %4BEAMER_col(Col) %10BEAMER_extra(Extra) %8BEAMER_opt(Opt)
 #
 # Software is all around us
 #
 #+INCLUDE: "prelude.org" :minlevel 1
 * Software source code
   :PROPERTIES:
   :CUSTOM_ID: main
   :END:
 ** Software is everywhere
    :PROPERTIES:
    :CUSTOM_ID: everywhere
    :END:
    #+latex: \begin{center}
    #+ATTR_LATEX: :width 0.7\linewidth
    file:software-center.pdf
    #+latex: \end{center}
 ** Source code matters!
   :PROPERTIES:
   :CUSTOM_ID: thesourcecode
   :END:
    #+LATEX: \includegraphics[width=.10\linewidth]{software.png}
    "The source code for a work means the preferred form of the work for making
    modifications to it." \hfill --- GPL Licence
 #+Beamer: \pause
 *** 
     :PROPERTIES:
     :BEAMER_env: block
     :BEAMER_act: +-
     :END:
 #+latex:    \begin{center} Hello World \end{center}
 *** Program (excerpt of binary) 			      :B_block:BMCOL:
     :PROPERTIES:
     :BEAMER_col: 0.5
     :BEAMER_env: block
     :BEAMER_act: +-
     :END:
 #+begin_src hex :exports code
   4004e6: 55             
   4004e7: 48 89 e5       
   4004ea: bf 84 05 40 00 
   4004ef: b8 00 00 00 00 
   4004f4: e8 c7 fe ff ff 
   4004f9: 90             
   4004fa: 5d             
   4004fb: c3             
 #+end_src
 *** Program (source code) 				      :B_block:BMCOL:
     :PROPERTIES:
     :BEAMER_col: 0.55
     :BEAMER_env: block
     :BEAMER_act: +-
     :END:
 
 #+begin_src c :exports code
 /* Hello World program */
 
 #include<stdio.h>
 
 void main()
 {
     printf("Hello World");
 }
 #+end_src
 ** Software Source Code is /special/
   :PROPERTIES:
   :CUSTOM_ID: softwareisdifferent
   :END:
 *** Harold Abelson, Structure and Interpretation of Computer Programs (1st ed.) \hfill (1985)
     /“Programs must be written for people to read, and only incidentally for machines to execute.”/
 #+BEAMER: \pause
-*** Apollo 11 source code ([[https://archive.softwareheritage.org/swh:1:cnt:64582b78792cd6c2d67d35da5a11bb80886a6409;origin=https://github.com/virtualagc/virtualagc;lines=245-261/][excerpt]])                           :B_block:BMCOL:
+*** Apollo 11 source code ([[https://archive.softwareheritage.org/swh:1:cnt:64582b78792cd6c2d67d35da5a11bb80886a6409;origin=https://github.com/virtualagc/virtualagc;visit=swh:1:snp:3c074afad81ad6b14d434b96e705e01d184752cf;anchor=swh:1:rev:007c2b95f301f9438b8b74d7993b7a3b9a66255b;path=/Luminary099/THE_LUNAR_LANDING.agc;lines=245-261/][excerpt]])                           :B_block:BMCOL:
     :PROPERTIES:
     :BEAMER_col: 0.48
     :BEAMER_env: block
     :END:
    #+LATEX: \includegraphics[width=\linewidth]{apollo-11-cranksilly.png}
    # excerpt of routine that asks astronaut to turn around the LEM
 #+BEAMER: \pause
-*** Quake III source code ([[https://archive.softwareheritage.org/swh:1:cnt:bb0faf6919fc60636b2696f32ec9b3c2adb247fe;origin=https://github.com/id-Software/Quake-III-Arena;lines=549-572/][excerpt]])                           :B_block:BMCOL:
+*** Quake III source code ([[https://archive.softwareheritage.org/swh:1:cnt:bb0faf6919fc60636b2696f32ec9b3c2adb247fe;origin=https://github.com/id-Software/Quake-III-Arena;visit=swh:1:snp:4ab9bcef131aaf449a7c01370aff8c91dcecbf5f;anchor=swh:1:rev:dbe4ddb10315479fc00086f08e25d968b4b43c49;path=/code/game/q_math.c;lines=549-572/][excerpt]])                           :B_block:BMCOL:
     :PROPERTIES:
     :BEAMER_col: 0.45
     :BEAMER_env: block
     :END:
    #+LATEX: \includegraphics[width=\linewidth]{quake-carmack-sqrt-1.png}
    # smart efficient implementation of 1/sqrt(x) on a CPU without special support
 #+BEAMER: \pause
 *** 							    :B_ignoreheading:
     :PROPERTIES:
     :BEAMER_env: ignoreheading
     :END:
 *** Len Shustek, Computer History Museum \hfill (2006)
     \hfill /“Source code provides a view into the mind of the designer.”/
    
 ** Source code is special, ctd
 *** Distinguishing features
     - /executable/ and /human readable/ knowledge (an /all time new/)
       + even hardware is... software! (VHDL, FPGA, ...)
       + /text files are forever/
     - naturally /evolves/ over time
       + the /development history/ is key to its /understanding/
     - complex: large /web of dependencies/, millions of SLOCs
 *** In a word
     - software /is not just another/ sequence of bits
     - a software archive /is not just another/ digital archive