diff --git a/src/tiempo.gmo b/src/tiempo.gmo
index 272b144..12a09ec 100644
--- a/src/tiempo.gmo
+++ b/src/tiempo.gmo
@@ -22,6 +22,7 @@ estuve leyendo, y recomiendo:
 
 => https://collapseos.org/ sitio de collapse os
 => https://www.opendemocracy.net/en/oureconomy/deep-adaptation-opens-necessary-conversation-about-breakdown-civilisation/ Deep Adaptation opens up a necessary conversation about the breakdown of civilisation
+=> https://dothemath.ucsd.edu/2011/10/the-energy-trap/ the energy trap | do the math
 
 ## sjm-1665