diff --git a/src/references.gmo b/src/references.gmo
index 271c1b4..de21aeb 100644
--- a/src/references.gmo
+++ b/src/references.gmo
@@ -50,21 +50,31 @@ texts by solderpunk in the {gemini} protocol
 
 # non-electronic computers
 			
+=> https://yip.pe/analog.html analogue computing
+
+
+## human-powered
 => https://wintermute.org/project/Rustic_Computing/ Brendan Howell - Rustic Computers
 => https://www.jeffreythompson.org/human-computers.php Jeff Thompson ++ Human Computers
-=> https://xkcd.com/505  - a bunch of rocks, randall munroe, xkcd
-=> http://www.blikstein.com/paulo/projects/project_water.html programmable water - paulo blikstein 2003	
+=> https://xkcd.com/505  a bunch of rocks, randall munroe, xkcd
+=> https://www.youtube.com/watch?v=rA5qnZUXcqo The Stilwell Brain - Vsauce (youtube)
+
+### paper
 => https://wiki.xxiivv.com/site/papier.html wdr papier computer
 => https://wiki.xxiivv.com/site/paper_computing.html paper computing
-=> https://yip.pe/analog.html analogue computing
-=> https://www.turingtumble.com/ turing tumble
-=> https://www.youtube.com/watch?v=rA5qnZUXcqo The Stilwell Brain - Vsauce (youtube)
-=> https://esoteric.codes/blog/escher-circuits-using-vision-to-perform-computation Escher Circuits: Using Vision to Perform Computation
-=> https://groups.csail.mit.edu/mac/users/bob/sliding-blocks.pdf The Complexity of Sliding-Block Puzzles and Plank Puzzles - Robert A. Hearn
 
-## fluidics-related
+
+## marbles
+
+=> https://www.turingtumble.com/ turing tumble
+=> https://www.youtube.com/watch?v=QKnSRw_X2w4 Rule 110 marble computer (youtube)
+
+## fluidics
 
 => ./fluidics.gmi {fluidics}
+=> http://www.blikstein.com/paulo/projects/project_water.html programmable water - paulo blikstein 2003	
+
+## dominoes
 => https://www.gwern.net/docs/www/think-maths.co.uk/5d2586e9724de4c5df5b354ee6117fcc2e1b722b.pdf Logic Gates - Domino Computer
 => https://www.omanobserver.om/article/44559/Business/aba-oman-students-set-world-record-for-dominoes-circuit ABA Oman students set world record for dominoes circuit
 
@@ -73,6 +83,10 @@ texts by solderpunk in the {gemini} protocol
 => https://www.media.mit.edu/projects/2d-an-exploration-of-drawing-as-programming-language-featuring-ideas-from-lambda-calculus/overview/ λ-2D: An Exploration of Drawing as Programming Language, Featuring Ideas from Lambda Calculus
 => https://tromp.github.io/cl/diagrams.html lambda diagrams
 
+## misc
+=> https://esoteric.codes/blog/escher-circuits-using-vision-to-perform-computation Escher Circuits: Using Vision to Perform Computation
+=> https://groups.csail.mit.edu/mac/users/bob/sliding-blocks.pdf The Complexity of Sliding-Block Puzzles and Plank Puzzles - Robert A. Hearn
+
 # dance and computers
 
 => https://www.analivia.com.br/computer-dance-3/ Computer Dance - Analivia Cordeiro