diff --git a/datev_export_dtvf_nitrokey/models/datev_export_dtvf.py b/datev_export_dtvf_nitrokey/models/datev_export_dtvf.py
index 99959e8..c6cb484 100644
--- a/datev_export_dtvf_nitrokey/models/datev_export_dtvf.py
+++ b/datev_export_dtvf_nitrokey/models/datev_export_dtvf.py
@@ -11,8 +11,11 @@ def _get_data_transaction(self, move):
         for data in super()._get_data_transaction(move):
             for line in move.line_ids:
                 for field_name in ("ref", "name", "move_name"):
-                    if (line[field_name] or "").startswith("SO") or (
-                        line[field_name] or ""
-                    ).startswith("EK"):
-                        data["Belegfeld 1"] = line[field_name]
+                    for token in (line[field_name] or "").split():
+                        if (
+                            token.startswith("SO")
+                            or token.startswith("EK")
+                            or token.startswith("GSV")
+                        ):
+                            data["Belegfeld 1"] = token
             yield data
diff --git a/datev_export_dtvf_nitrokey/tests/__init__.py b/datev_export_dtvf_nitrokey/tests/__init__.py
new file mode 100644
index 0000000..f3f2b44
--- /dev/null
+++ b/datev_export_dtvf_nitrokey/tests/__init__.py
@@ -0,0 +1 @@
+from . import test_datev_export_dtvf_nitrokey
diff --git a/datev_export_dtvf_nitrokey/tests/test_datev_export_dtvf_nitrokey.py b/datev_export_dtvf_nitrokey/tests/test_datev_export_dtvf_nitrokey.py
new file mode 100644
index 0000000..370f132
--- /dev/null
+++ b/datev_export_dtvf_nitrokey/tests/test_datev_export_dtvf_nitrokey.py
@@ -0,0 +1 @@
+from odoo.addons.datev_export_dtvf.tests.test_datev_export_dtvf import TestDatevExportDtvf