[Autor nieustalony, Mrozoodporne kaktusy i Program ochrony kaktusów, b.d.q]
Older pages on frost-hardy cacti and a plant protection document, preserved in Konrad Szychowski's private materials archive. The “Kaktusy mrozoodporne” copy, saved in November 2010, contains 16 collection entries, an account of several nights at −4°C and 954 temperature-list entries for cacti and other succulents. It gives older plant identifications and threshold values. Measurement methods, exposure duration and injury criteria remain unspecified. The old page's publication date and account authorship are undetermined.
Copy in the supplied material