diff --git a/doc/api/core/observable.md b/doc/api/core/observable.md
index cb88d3362..ab76e124f 100644
--- a/doc/api/core/observable.md
+++ b/doc/api/core/observable.md
@@ -113,6 +113,7 @@ The Observer and Observable interfaces provide a generalized mechanism for push-
 - [`let`](operators/let.md)
 - [`manySelect`](operators/manyselect.md)
 - [`map`](operators/select.md)
+- [`materialize`](operators/materialize.md)
 - [`max`](operators/max.md)
 - [`maxBy`](operators/maxby.md)
 - [`merge`](operators/mergeproto.md)