diff --git a/dhp-common/src/main/java/eu/dnetlib/dhp/schema/oaf/utils/IdentifierFactory.java b/dhp-common/src/main/java/eu/dnetlib/dhp/schema/oaf/utils/IdentifierFactory.java
index fc553ced10..2c4cd29e88 100644
--- a/dhp-common/src/main/java/eu/dnetlib/dhp/schema/oaf/utils/IdentifierFactory.java
+++ b/dhp-common/src/main/java/eu/dnetlib/dhp/schema/oaf/utils/IdentifierFactory.java
@@ -52,6 +52,9 @@ public class IdentifierFactory implements Serializable {
 		PID_AUTHORITY.put(PidType.pmid, HashBiMap.create());
 		PID_AUTHORITY.get(PidType.pmid).put(EUROPE_PUBMED_CENTRAL_ID, "Europe PubMed Central");
 		PID_AUTHORITY.get(PidType.pmid).put(PUBMED_CENTRAL_ID, "PubMed Central");
+
+		PID_AUTHORITY.put(PidType.arXiv, HashBiMap.create());
+		PID_AUTHORITY.get(PidType.arXiv).put(ARXIV_ID, "arXiv.org e-Print Archive");
 	}
 
 	/**
diff --git a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java
index f2e6a5a306..68e37b9b78 100644
--- a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java
+++ b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java
@@ -11,11 +11,12 @@ public class ModelConstants {
 	public static final String ORCID_PENDING = "orcid_pending";
 	public static final String ORCID_CLASSNAME = "Open Researcher and Contributor ID";
 
-	public static String CROSSREF_ID = "10|openaire____::081b82f96300b6a6e3d282bad31cb6e2";
-	public static String DATACITE_ID = "10|openaire____::9e3be59865b2c1c335d32dae2fe7b254";
+	public static final String CROSSREF_ID = "10|openaire____::081b82f96300b6a6e3d282bad31cb6e2";
+	public static final String DATACITE_ID = "10|openaire____::9e3be59865b2c1c335d32dae2fe7b254";
 
-	public static String EUROPE_PUBMED_CENTRAL_ID = "10|opendoar____::8b6dd7db9af49e67306feb59a8bdc52c";
-	public static String PUBMED_CENTRAL_ID = "10|opendoar____::eda80a3d5b344bc40f3bc04f65b7a357";
+	public static final String EUROPE_PUBMED_CENTRAL_ID = "10|opendoar____::8b6dd7db9af49e67306feb59a8bdc52c";
+	public static final String PUBMED_CENTRAL_ID = "10|opendoar____::eda80a3d5b344bc40f3bc04f65b7a357";
+	public static final String ARXIV_ID = "10|opendoar____::6f4922f45568161a8cdf4ad2299f6d23";
 
 	public static final String DNET_SUBJECT_TYPOLOGIES = "dnet:subject_classification_typologies";
 	public static final String DNET_RESULT_TYPOLOGIES = "dnet:result_typologies";