diff --git a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
index 762e5fd5..61470d08 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
@@ -133,6 +133,7 @@ module Beta = {
   }
 
   let fromMeanAndStdev = (mean, stdev) => {
+    // https://en.wikipedia.org/wiki/Beta_distribution#Mean_and_variance
     let var = stdev *. stdev
     let sampleSize = mean *. (1.0 -. mean) /. var
     mean->fromMeanAndSampleSize(sampleSize)