diff --git a/src/config/sidebar.yml b/src/config/sidebar.yml
index 49ad0c9aebaae96b950cb8d909531d75722fc34a..2393b665de6d44ea9901c80dcdf1c9f484599459 100644
--- a/src/config/sidebar.yml
+++ b/src/config/sidebar.yml
@@ -34,6 +34,8 @@
       link: 'https://dd4hep.web.cern.ch/dd4hep/page/users-manual/'
     - label: 'XML tags and attributes'
       link: 'https://github.com/AIDASoft/DD4hep/blob/master/DDCore/include/XML/UnicodeValues.h'
+    - label: 'NPdet Documenation'
+      link: 'https://eic.phy.anl.gov/npdet/'
     - label: 'Links'
       link: '/links'
       #- label: Usage
diff --git a/src/docs/part1/simple_detector.md b/src/docs/part1/simple_detector.md
index 4e881f1137d54861d092e83dc7aefd7fec7d14b9..1a3df764755a87905a441556de0c0fa01f2ace5b 100644
--- a/src/docs/part1/simple_detector.md
+++ b/src/docs/part1/simple_detector.md
@@ -121,16 +121,19 @@ npsim  --runType run  --enableG4GPS \
 
 This will run geant4 using the General Particle Source (GPS) tool.
 The output will be a root file containing the generated events and GEM tracker hits.
+Look at [gps.mac](https://eicweb.phy.anl.gov/EIC/tutorials/ip6_tutorial_1/-/blob/master/gps.mac).
 
-See the [GPS Documentation](http://www.fe.infn.it/u/paterno/Geant4_tutorial/slides_further/GPS/GPS.pdf) for more information.
+Refer to the [GPS Documentation](http://www.fe.infn.it/u/paterno/Geant4_tutorial/slides_further/GPS/GPS.pdf) for more setup possibilities.
 
 ## Using detector description in analysis
 
 ### Preface: data model
 
-First, the data model used by `npsim is described here
-https://eic.phy.anl.gov/eicd/
+First, the geant4 output data model used by `npsim` is [described in a single yaml file](https://eicweb.phy.anl.gov/EIC/NPDet/-/blob/master/src/dd4pod/dd4hep.yaml).
+Note that this is purposefully factorized from the larger EIC data model, `eicd`, which is used 
+at every step post geant4.
 
+https://eic.phy.anl.gov/eicd/
 
 Look at the generated file in results:
 ![local hit position](../hit_position.png)
@@ -184,6 +187,7 @@ root -b -q scripts/tutorial3_id_spec.cxx+
   auto layer_index = decoder->index("layer");
   fmt::print(" \"layer\" index is {}.\n", layer_index);
 ```
+See [BitFieldCoder documentation](https://dd4hep.web.cern.ch/dd4hep/reference/classdd4hep_1_1DDSegmentation_1_1BitFieldCoder.html) documentation for more details.
 
 Later in the loop over event hits.
 ```cpp
@@ -207,6 +211,12 @@ system:0:8,barrel:8:2,layer:10:4,module:14:12,sensor:26:2,x:32:-16,y:48:-16
  "layer" index is 2.
 ```
 
-For more information, see the [BitFieldCoder documentation](https://dd4hep.web.cern.ch/dd4hep/reference/classdd4hep_1_1DDSegmentation_1_1BitFieldCoder.html).
 
+## References
+
+- [NPdet](https://eic.phy.anl.gov/npdet/)
+- [BitFieldCoder documentation](https://dd4hep.web.cern.ch/dd4hep/reference/classdd4hep_1_1DDSegmentation_1_1BitFieldCoder.html) documentation
+- [List of DD4hep Segmentations](https://github.com/AIDASoft/DD4hep/tree/master/DDCore/include/DDSegmentation)
+- [List of DD4hep detector constructors](https://github.com/AIDASoft/DD4hep/tree/master/DDDetectors/src)
+- [Compact description examples](https://github.com/AIDASoft/DD4hep/tree/master/DDDetectors/compact/SiD), and [more examples](https://github.com/AIDASoft/DD4hep/tree/master/examples/ClientTests/compact)