private void outlineTravel(PRIndirectReference outline) {
        while (outline != null) {
            PdfDictionary outlineR = (PdfDictionary)PdfReader.getPdfObjectRelease(outline);
            PRIndirectReference first = (PRIndirectReference)outlineR.get(PdfName.FIRST);
            if (first != null) {
                outlineTravel(first);
            }
            PdfReader.killIndirect(outlineR.get(PdfName.DEST));
            PdfReader.killIndirect(outlineR.get(PdfName.A));
            PdfReader.killIndirect(outline);
            outline = (PRIndirectReference)outlineR.get(PdfName.NEXT);
        }
    }