Tài liệu tham khảo WikiPedia: PDFCreator http://en.pdfforge.org/pdfcreator http://www.pdfforge.org/node/1975 https://github.com/pdfforge/PDFCreator https://web.archive.org/web/20081229041205/http://... https://www.wikidata.org/wiki/Q1143775#P1324
