diff --git a/e-invoice-api/src/main/kotlin/net/codinux/invoicing/api/InvoicingResource.kt b/e-invoice-api/src/main/kotlin/net/codinux/invoicing/api/InvoicingResource.kt
index 1ad537a..ce3b7cc 100644
--- a/e-invoice-api/src/main/kotlin/net/codinux/invoicing/api/InvoicingResource.kt
+++ b/e-invoice-api/src/main/kotlin/net/codinux/invoicing/api/InvoicingResource.kt
@@ -59,14 +59,14 @@ class InvoicingResource(
     @POST
     @Consumes(MediaType.APPLICATION_OCTET_STREAM)
     @Produces(MediaType.APPLICATION_JSON)
-    @Operation(summary = "Extract invoice data from a Factur-x / ZUGFeRD or XRechnung file")
+    @Operation(summary = "Extract invoice data from a Factur-X / ZUGFeRD or XRechnung file")
     fun extractInvoiceData(invoice: FileUpload) =
         service.extractInvoiceData(invoice.uploadedFile())
 
     @Path("validate")
     @POST
     @Consumes(MediaType.APPLICATION_OCTET_STREAM)
-    @Operation(summary = "Validate a Factur-x / ZUGFeRD or XRechnung file")
+    @Operation(summary = "Validate a Factur-X / ZUGFeRD or XRechnung file")
     fun validateInvoiceXml(invoice: FileUpload) =
         service.validateInvoice(invoice.uploadedFile()).reportAsXml
 
diff --git a/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/converter/EInvoiceConverter.kt b/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/converter/EInvoiceConverter.kt
index db5f3a5..80b8285 100644
--- a/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/converter/EInvoiceConverter.kt
+++ b/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/converter/EInvoiceConverter.kt
@@ -30,12 +30,12 @@ class EInvoiceConverter {
 
 
     /**
-     * Converts a CII (Cross Industry Invoice) invoice, e.g. a Zugferd or Factur-X invoice, to UBL (Universal Business Language).
+     * Converts a CII (Cross Industry Invoice) invoice, e.g. a ZUGFeRD or Factur-X invoice, to UBL (Universal Business Language).
      */
     fun convertCiiToUbl(invoice: Invoice) = convertCiiToUbl(createXRechnungXml(invoice))
 
     /**
-     * Converts a CII (Cross Industry Invoice) invoice, e.g. a Zugferd or Factur-X invoice, to UBL (Universal Business Language).
+     * Converts a CII (Cross Industry Invoice) invoice, e.g. a ZUGFeRD or Factur-X invoice, to UBL (Universal Business Language).
      */
     fun convertCiiToUbl(invoiceXml: String): String {
         // TODO: extract a common method for this
@@ -54,7 +54,7 @@ class EInvoiceConverter {
     }
 
     /**
-     * Converts a CII (Cross Industry Invoice) invoice, e.g. a Zugferd or Factur-X invoice, to UBL (Universal Business Language).
+     * Converts a CII (Cross Industry Invoice) invoice, e.g. a ZUGFeRD or Factur-X invoice, to UBL (Universal Business Language).
      */
     fun convertCiiToUbl(xmlFile: File, outputFile: File) {
         val cii2Ubl = CIIToUBL()