diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 1dfa93b..1148cf8 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,7 +12,7 @@ repos:
       - id: check-useless-excludes
 
   - repo: https://github.com/ComPWA/policy
-    rev: 0.2.0
+    rev: 0.2.2
     hooks:
       - id: colab-toc-visible
       - id: check-dev-files
diff --git a/README.md b/README.md
index 42e482d..a82f8ac 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ where $Z_{l}^{m}(\Omega,\Phi)=Y_{l}^{m}(\Omega)e^{-i\Phi}$ is a phase-rotated sp
 
 ![](docs/fig/feynman-gluex-two-pseudoscalar.svg)
 
-The amplitude model is implemented in [AmpTools](https://github.com/mashephe/AmpTools) and symbolically in Python using [SymPy](https://docs.sympy.org) with additional tools from [`amptools`](https://ampform.rtfd.io) ([ComPWA](https://compwa-org.rtfd.io)). Dynamics are not yet included (model-indepedent by binning over energy). So we are just comparing linar combinations of spherical harmonics, but the comparison can be extended by investigating final states with a vector meson and/or parametrizing dynamic lineshapes.
+The amplitude model is implemented in [AmpTools](https://github.com/mashephe/AmpTools) and symbolically in Python using [SymPy](https://docs.sympy.org) with additional tools from [`amptools`](https://ampform.rtfd.io) ([ComPWA Project](https://compwa.github.io)). Dynamics are not yet included (model-indepedent by binning over energy). So we are just comparing linar combinations of spherical harmonics, but the comparison can be extended by investigating final states with a vector meson and/or parametrizing dynamic lineshapes.
 
 ![](docs/fig/feynman-gluex-vector-meson.svg)
 
diff --git a/environment.yml b/environment.yml
index 9070a96..1450e9f 100644
--- a/environment.yml
+++ b/environment.yml
@@ -2,7 +2,7 @@ name: gluex-amplitude
 channels:
   - defaults
 dependencies:
-  - python==3.8.*
+  - python==3.9.*
   - pip
   - pip:
       - -e .[dev]