They're the first two publications to the "Moderný Pračlovek" series (Modern day Caveman). The key strategy was to characterize caveman drawings in a very simple way and products that were utilized At the moment... but also within our days. The main one particular — “Kuchyňa Pračloveka” (Caveman's Kitchen area) — https://maplepublishers.com/blog/how-to-start-your-career-as-a-self-publishing-author-with-maple-publishing/