diff --git a/src/Mindee/Parsing/Invoice/InvoiceV4Prediction.cs b/src/Mindee/Parsing/Invoice/InvoiceV4Prediction.cs
index 28199ddc..2b59c7d0 100644
--- a/src/Mindee/Parsing/Invoice/InvoiceV4Prediction.cs
+++ b/src/Mindee/Parsing/Invoice/InvoiceV4Prediction.cs
@@ -12,6 +12,12 @@ namespace Mindee.Parsing.Invoice
     [Endpoint("invoices", "4")]
     public sealed class InvoiceV4Prediction : FinancialPredictionBase
     {
+        /// <summary>
+        /// List of Reference numbers including PO number.
+        /// </summary>
+        [JsonPropertyName("reference_numbers")]
+        public List<StringField> ReferenceNumbers { get; set; }
+
         /// <summary>
         /// The supplier name.
         /// </summary>
@@ -105,6 +111,7 @@ public override string ToString()
             StringBuilder result = new StringBuilder("----- Invoice V4 -----\n");
             result.Append($"Locale: {Locale}\n");
             result.Append($"Invoice number: {InvoiceNumber.Value}\n");
+            result.Append($"Reference numbers: {string.Join(", ", ReferenceNumbers.Select(rn => rn.Value))}\n");
             result.Append($"Invoice date: {Date.Value}\n");
             result.Append($"Invoice due date: {DueDate.Value}\n");
             result.Append($"Supplier name: {SupplierName.Value}\n");
diff --git a/tests/resources b/tests/resources
index 134c591b..4c2508be 160000
--- a/tests/resources
+++ b/tests/resources
@@ -1 +1 @@
-Subproject commit 134c591bc79e8309dc54a552080a056769795dbb
+Subproject commit 4c2508bebeedb6657a5dc42375920029b2456442