diff --git a/docs/api/effect.rst b/docs/api/effect.rst
new file mode 100644
index 0000000..298086e
--- /dev/null
+++ b/docs/api/effect.rst
@@ -0,0 +1,6 @@
+dilax.effect
+================
+
+.. automodule:: dilax.effect
+    :show-inheritance:
+    :members:
diff --git a/docs/api/index.rst b/docs/api/index.rst
index 8045cda..8c84c45 100644
--- a/docs/api/index.rst
+++ b/docs/api/index.rst
@@ -4,8 +4,10 @@ API Reference
 .. toctree::
    :maxdepth: 3
 
+   effect
    likelihood
    model
+   modifier
    optimizer
    parameter
    pdf
diff --git a/docs/api/modifier.rst b/docs/api/modifier.rst
new file mode 100644
index 0000000..cc706f7
--- /dev/null
+++ b/docs/api/modifier.rst
@@ -0,0 +1,6 @@
+dilax.modifier
+================
+
+.. automodule:: dilax.modifier
+    :show-inheritance:
+    :members:
diff --git a/src/dilax/modifier.py b/src/dilax/modifier.py
index 91a76c9..bfd4ad1 100644
--- a/src/dilax/modifier.py
+++ b/src/dilax/modifier.py
@@ -396,7 +396,7 @@ def prepare(
                 if self.mode == self.Mode.barlow_beeston_lite and not mask[i]:
                     # we merge all processes into one parameter
                     # for the barlow-beeston-lite approach where
-                    # the bin content is above a certain treshold
+                    # the bin content is above a certain threshold
                     pkey = f"{i}"
                 process_parameters[pkey] = Parameter(value=jnp.array(0.0))
             # prepare staterror