They're the first two publications with the "Moderný Pračlovek" series (Modern-day Caveman). The primary concept was to characterize caveman drawings within a very simple way and products which have been employed at that time... but will also in our times. The first just one — “Kuchyňa Pračloveka” (Caveman's Kitchen) — https://maplepublishers.com/blog/5-tips-to-find-the-best-self-publishing-companies-uk/