diff --git a/computer_design/index.html b/computer_design/index.html
index 6b3b52e2d3396c2853380ca6e5bbb90da77f5db8..19cf51b425fa5491ab6b15340061f05108c85367 100755
--- a/computer_design/index.html
+++ b/computer_design/index.html
@@ -72,9 +72,10 @@ sketching<br>
 <a href=http://pixologic.com/>ZBrush</a> <a href=https://stephaneginier.com/sculptgl>SculptGL</a> <a href=https://nomadsculpt.com>Nomad</a><br>
 <a href=http://www.rhino3d.com/>Rhino</a> <a href=http://www.grasshopper3d.com/>Grasshopper</a> <a href=http://kangaroo3d.com/>Kangaroo</a> <br>
 <a href=http://solvespace.com/index.pl>Solvespace</a><br>
-<a href=http://www.freecadweb.org>FreeCAD</a> <a href=https://dev.opencascade.org>Open CASCADE</a> <a href=https://ondsel.com/>Ondsel</a><br>
+<a href=http://www.freecadweb.org>FreeCAD</a> <a href=https://dev.opencascade.org>Open CASCADE</a><br>
 <div style="margin-left:2.5%">
 <a href=workbenches.mp4>workbenches</a>
+<a href=https://github.com/geolta/FreeCAD-Ribbon>ribbon</a>
 <a href=snaps.mp4>snaps</a>
 <a href=coordinates.mp4>coordinates containers</a>
 <a href=extrude.mp4>extrude</a>
@@ -113,12 +114,15 @@ sketching<br>
 <a href=antimony.mp4>adaptively sampled distance fields (ASDF)</a><br>
 </div>
 <a href=https://ntopology.com/>nTopology</a><br>
-<a href=https://grabcad.com/>GrabCAD</a> <a href=https://help.grabcad.com/article/64-3d-viewer?locale=en>viewer</a><br>
+<a href=https://sketchfab.com/>Sketchfab</a> <a href=https://modelviewer.dev/>model-viewer</a>
+<br>
+
 </div>
 
 <b><i>interchange formats</i></b>
 <div style="margin-left:2.5%">
 <s><i>DXF</i></s><br>
+<a href=https://developer.mozilla.org/en-US/docs/Web/SVG>SVG</a><br>
 <a href=../scanning_printing/index.html>STL</a><br>
 <a href=https://en.wikipedia.org/wiki/Wavefront_.obj_file>OBJ</a><br>
 <a href=https://www.autodesk.com/products/fbx/overview>FBX</a><br>
@@ -147,7 +151,6 @@ sketching<br>
 <a href=https://www.sculptrvr.com>SculptrVR</a><br>
 <a href=https://www.gravitysketch.com>Gravity Sketch</a><br>
 <a href=https://www.kodon.xyz>Kodon</a><br>
-<a href=https://www.tiltbrush.com>Tilt Brush</a><br>
 </div>
 
 <b><a href=http://fab.cba.mit.edu/classes/MAS.864/><i>simulation</i></a></b><br>
diff --git a/computer_design/video.html b/computer_design/video.html
index 48995a40a81374a04b0259892ecafe2aaa813cc4..175afe0bffea16ef1c2c3e9ae871dd1be4bd0e02 100644
--- a/computer_design/video.html
+++ b/computer_design/video.html
@@ -8,6 +8,8 @@ codecs
    H.264: good compression, widely supported
    H.265: better compression, less widely supported
 
+~megabytes/minute compression for Web
+
 variable bit rate 1080p MP3:
 
    ffmpeg -i input_video -vcodec libx264 -crf 25 -preset medium -vf scale=-2:1080 -acodec libmp3lame -q:a 4 -ar 48000 -ac 2 output_video.mp4
diff --git a/project_management/index.html b/project_management/index.html
index c905234ceafbb39d4494b7cfe237087d88c05bad..894d663f1eaa1f3b0fb8b9303222c1846a9d9228 100755
--- a/project_management/index.html
+++ b/project_management/index.html
@@ -37,6 +37,7 @@
    <a href=http://brackets.io/>Brackets</a> <a href=https://phcode.dev/>Phoenix</a>
    <a href=https://eclipse.org/>Eclipse</a> <a href=https://code.visualstudio.com>Visual Studio</a>
    <a href=http://www.libreoffice.org/>LibreOffice</a> <a href=http://www.seamonkey-project.org/>SeaMonkey</a> <a href=http://www.adobe.com/products/dreamweaver.html>Dreamweaver</a>
+   <a href=https://www.notion.com/help/export-your-content>Notion</a>
    <a href=../interface_application_programming/index.html>JavaScript</a> <a href=http://getbootstrap.com>Bootstrap</a> <a href=https://jquery.com>jQuery</a>
    <a href=https://docs.gitlab.com/ee/user/markdown.html>Markdown</a> <a href=https://github.com/markserv/markserv>Markserv</a> <a href=https://github.com/Naereen/Strapdown.js/>Strapdown.js</a> <a href=http://pandoc.org>Pandoc</a> <a href=https://gohugo.io>Hugo</a> <a href=https://jekyllrb.com>Jekyll</a> <a href=https://vuepress.vuejs.org/>VuePress</a> <a href=https://www.mkdocs.org>MkDocs</a>
    <a href=https://about.gitlab.com/features/gitlab-ci-cd>CI/CD</a> <a href=http://yaml.org>YAML</a>