diff --git a/src/doc/concepts.rst b/src/doc/concepts.rst
index bbaf8618f2402f8db228331623380af263c2ddc6..0f602f7ed4fd7b6c503c2abde54febf705d96d05 100644
--- a/src/doc/concepts.rst
+++ b/src/doc/concepts.rst
@@ -11,7 +11,8 @@ of the existing data (For example could a tree of Python file objects
 (StructureElements) represent a file tree that exists on some file server).
 
 Relevant sources in:
-src/structure_elements.py
+
+- ``src/structure_elements.py``
 
 Converters
 ++++++++++
@@ -22,12 +23,12 @@ the above named tree. The definition of a Converter also contains what
 Converters shall be used to treat the generated child-StructureElements. The
 definition is therefore a tree itself.
 
-See `:doc:converters<converters>` for details.
+See :std:doc:`converters<converters>` for details.
 
 
 
 Relevant sources in:
-src/converters.py
+- ``src/converters.py``
 
 
 
@@ -37,7 +38,7 @@ Identifiables
 An Identifiable of a Record is like the fingerprint of a Record.
 
 The identifiable contains the information that is used by the CaosDB Crawler to identify Records.
-In order to check whether a Record exits in the CaosDB Server, the CaosDB Crawler creates a query 
+In order to check whether a Record exits in the CaosDB Server, the CaosDB Crawler creates a query
 using the information contained in the Identifiable.
 
 For example, suppose a certain experiment is at most done once per day, then the identifiable could
@@ -51,13 +52,19 @@ with two Properties with the name 'a' or if 'a' is a list containing at least th
 The path of a File object can serve as a Property that identifies files and similarly the name of 
 Records can be used.
 
-An identifiable can only use one RecordType eventhough the identified Records might have multiple
+An identifiable can only use one RecordType even though the identified Records might have multiple
 Parents.
 
 Relevant sources in:
 
-- src/identifiable_adapters.py
-- src/identifiable.py
+- ``src/identifiable_adapters.py``
+- ``src/identifiable.py``
+
+RegisteredIdentifiables
++++++++++++++++++++++++
+A Registered Identifiable is the blue print for Identifiables. RegisteredIdentifiables are
+associated with RecordTypes and define of what information an identifiable for that RecordType
+exists. There can be multiple Registered Identifiables for one RecordType.
 
 The Crawler
 +++++++++++
@@ -67,7 +74,8 @@ The crawler can be considered the main program doing the synchronization in basi
 #. Compare the current state of the CaosDB instance with the set of CaosDB Entities created in step 1, taking into account the :ref:`registered identifiables<Identifiables>`. Insert or update entites accordingly.
 
 Relevant sources in:
-src/crawl.py
+
+- ``src/crawl.py``