diff --git a/Database.md b/Database.md
index 5a68eea..64f3523 100644
--- a/Database.md
+++ b/Database.md
@@ -86,9 +86,11 @@ Creative Commons licenses are commonly used to govern the use and distribution o
 
  
 ## Dataset references & identifiers
-During the ingestion of the new dataset, there is the possibility to refer to existing publications (table 'document_references') through persistent Identifier (PID). Such identifiers are precisely defined and described in Tethys RDR under the metadata element "Dataset References" as identifier types: DOI, HANDLE, ISBN, URL, and URN. ([manual, p. 21](https://tethys.at/docs/HandbuchTethys.pdf#page=22)). Self referencing identifiers of a dataset are stored inside the table 'document_identifiers'.
+During the ingestion of the new dataset, there is the possibility to refer to existing publications (table 'document_references') through persistent Identifier (PID). Such identifiers are precisely defined and described in Tethys RDR under the metadata element "Dataset References" as identifier types: DOI, HANDLE, ISBN, URL, and URN. (<a href="https://tethys.at/docs/HandbuchTethys.pdf#page=22" target="_blank">manual, p. 21</a>). 
 
-In addition, the relation types (the kind of relationship) are precisely defined ([manual, p. 22](https://tethys.at/docs/HandbuchTethys.pdf#page=23)). In most cases, the relation type “IsNewVersionOf” will be used.
+Self referencing identifiers of a dataset are stored inside the table 'document_identifiers'.
+
+In addition, the relation types (the kind of relationship) are precisely defined (<a href="https://tethys.at/docs/HandbuchTethys.pdf#page=23" target="_blank">manual, p. 22</a>). In most cases, the relation type “IsNewVersionOf” will be used.
 
 ![title](./tethys_references.png)
 * **document_identifiers**: