Bertrand Charlas was a member of Chott's art studios. He illustrated several episodes of the Tarzan-like 'Zembla' series for Zembla-Special. For Special-Kiwi and Special-Rodeo, he drew the 'Billy Wild' series, about a western crimefighter and his Mexican sidekick Pancho. Remarkable is the resemblance to Jijé's Jerry Spring, who also has a Mexican friend called Pancho.