To learn about the Yeti, which he depicted as a benevolent creature, Hergé contacted his friend Bernard Heuvelmans, the author of On the Trail of Unknown Animals.
Untuk memahami soal Yeti, yang ia gambarkan sebagai sesosok makhluk yang berkebajikan, Hergé mengkontak temannya Bernard Heuvelmans, pengarang On the Trail of Unknown Animals.