diff --git a/smnp.audio.synth.md b/smnp.audio.synth.md
index cbe0c13..50a8d56 100644
--- a/smnp.audio.synth.md
+++ b/smnp.audio.synth.md
@@ -76,9 +76,6 @@ So the corresponding points of stages can be calculated as follows:
 * `p2x = p2 * L = 0.4 * 10000 = 4000`
 * `p3x = p3 * L = 0.8 * 10000 = 8000`
 
-##### Factory function
-The [[smnp.audio.synth#adsr]] is factory function for _ADSR_ envelope.
-
 ##### Example
 ```
 wave1 = wave({ envelope -> adsr(0.2, 0.4, 0.7, 0.7) }, [@c:8]);
@@ -97,9 +94,6 @@ The _constant_ envelope does not change the sound shape at all. Technically, it
 Following plot shows the constant envelope shape:
 [[plots/envelopes/constant.svg]]
 
-##### Factory function
-The [[smnp.audio.synth#constant]] is factory function for _constant_ envelope.
-
 ##### Example
 ```
 overtones = [1.0];