Due to its longevity, older editions (which still contain timeless mathematical and physical formulas) are frequently found in libraries or second-hand shops. Bibliotheek Wetteren History of Publication Original launch by PBNA as a diary-table book hybrid. Mid-20th Century:
: Official digital versions are often provided via professional licenses or institutional libraries. Publicly available snippets or older digitized versions (e.g., home.deds.nl polytechnisch zakboek pdf