PDFlib GmbH founder Thomas Merz wrote a few books which had some impact in the PostScript and PDF community. Although no longer supported, this material is provided on an »as is« basis.
The pdfmark primer
The pdfmark primer gives easy-to-use examples for leveraging a powerful technique for generating hypertext elements in PDF using special PostScript commands. Available in English and German.
Die PostScript -& PDF-Bibel
Thomas Merz' well-known book on the intrinsics of PostScript and PDF. Available in German only.