diff --git a/trolley_problem.myco b/trolley_problem.myco
index 74ef11b..cff8056 100644
--- a/trolley_problem.myco
+++ b/trolley_problem.myco
@@ -1,3 +1,3 @@
 The trolley problem is an [[ethical]] [[thought experiment]]. In it, a trolley is moving fast down a track towards a switch. There are two tracks beyond this, on which one and five people respectively are tied up. If the trolley is not stopped, it will run over five people, killing them; the switch can divert it onto the second track, with just one person on it.
 
-The trolley problem is easily solved by [[Newtonian spatially corrected total utilitarianism]], the correct [[ethical system]].
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+The trolley problem is easily solved by [[Newtonian spatially corrected total utilitarianism]], the correct [[ethical system]], as explained in [[https://osmarks.net/stuff/jor/newtonian_ethics.html|Implications Of a Newtonian Model for Spatially-Varying Ethical Reasoning and Considerations on Multi-Event Moral Significance Scaling]].
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