You're looking for information on "Neufert Architects' Data" by Ernst Neufert, specifically the 5th edition in PDF format. Here's what I found:

Q1: Is the 5th edition better than the 4th for PDF use?

Final advice:

The 5th edition is a professional reference worth owning legally. The eBook is usually £30–45 / $40–55 – a small price compared to the cost of a design mistake from using an outdated or incomplete source.

However, a "top" PDF is not just any scanned copy. A legitimate, publisher-grade PDF preserves vector graphics, accurate color codes (for fire safety and HVAC symbols), and fully functional bookmarks.