Merge multiple PDF files to Single PDF file in WPF c#

var originalDocument = PDDocument.load(@"C:\\temp\\1.pdf");
 var originalCatalog = originalDocument.getDocumentCatalog();
 java.util.List sourceDocumentPages = originalCatalog.getAllPages();

 var originalDocument2 = PDDocument.load(@"C:\temp\2.pdf");
 var originalCatalog2 = originalDocument.getDocumentCatalog();
 java.util.List sourceDocumentPages2 = originalCatalog.getAllPages();

 var newDocument = new PDDocument();
 newDocument.addPage((PDPage)sourceDocumentPages.get(1));
 newDocument.addPage((PDPage)sourceDocumentPages2.get(1));


 newDocument.save(@"C:\temp\merge.pdf");

Quote:

{"Could not load file or assembly 'commons-logging, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. A strongly-named assembly is required. (Exception from HRESULT: 0x80131044)":"commons-logging, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"}