diff --git a/UtilitatPdf/MainWindow.xaml.cs b/UtilitatPdf/MainWindow.xaml.cs
index 5e449a4..0d3df7b 100644
--- a/UtilitatPdf/MainWindow.xaml.cs
+++ b/UtilitatPdf/MainWindow.xaml.cs
@@ -153,12 +153,8 @@ namespace UtilitatPdf
                         try
                         {
                             PdfMergeFiles mClas = new PdfMergeFiles(FinalPdfFile);
-
-                            foreach (PdfInfo fi in list)
-                            {
-                                mClas.AddFile(fi.FileName);
-                            }
-                            mClas.Copy();
+                            mClas.AddFiles(list);
+                            mClas.Generate();
                         }
                         catch (IOException ex)
                         {
diff --git a/UtilitatPdf/PdfMergeFiles.cs b/UtilitatPdf/PdfMergeFiles.cs
index 80a50e2..145a756 100644
--- a/UtilitatPdf/PdfMergeFiles.cs
+++ b/UtilitatPdf/PdfMergeFiles.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.ObjectModel;
 using System.IO;
 using iText.Kernel.Pdf;
 using iText.Kernel.Utils;
@@ -31,9 +32,19 @@ namespace UtilitatPdf
                 {
                     if (new FileInfo(_FinalPdfFile).Exists) File.Delete(_FinalPdfFile);
                 }
-
             }
         }
+        public bool AddFiles(ObservableCollection<PdfInfo> sourceFiles)
+        {
+            foreach (PdfInfo fitxer in sourceFiles)
+            {
+                if (!this.AddFile(fitxer.FileName))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
         public bool AddFile(string PdfFilename)
         {
             checkVars(PdfFilename);
@@ -52,7 +63,7 @@ namespace UtilitatPdf
                     _pdfMerger = new PdfMerger(_pdfDocument);
                     _pdfMerger.Merge(_pdfDocument2, 1, _pdfDocument2.GetNumberOfPages());
 
-                    this.Close();
+                    this.ClosePdfDocs();
                 }
                 catch (IOException)
                 {
@@ -72,11 +83,11 @@ namespace UtilitatPdf
             }
             return true;
         }
-        public void Copy()
+        public void Generate()
         {
             File.Copy(_tmpFile, _FinalPdfFile);
         }
-        private void Close()
+        private void ClosePdfDocs()
         {
             _pdfDocument?.Close();
             _pdfDocument2?.Close();