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WikiPedia: PDFtk http://www.accesspdf.com/pdftk/ http://www.pdfhacks.com/pdftk/ http://www.pdflabs.com/docs/pdftk-version-history/ http://www.pdflabs.com/tools/pdftk-the-pdf-toolkit... https://www.pdflabs.com/tools/pdftk-the-pdf-toolki...