When Frank Sels left the Studio in 1967, Karel Biddeloo took over most of the realistic series of Vandersteen. He made "Karl May" from 1967 until 1969, when the Bessy-studio took over the job. He also took over "Biggles", which ended in 1969, when it was replaced by the jungle series "Safari", inspired by "Daktari". At the start of the series, Vandersteen did most of the creative work, but after a few albums he left most of the work to Biddeloo. The series ended in 1974. Biddeloo then devoted most of his time to "De Rode Ridder", where he started inking the stories by Vandersteen in 1967 and took completely over in 1969, when Vandersteen lost his interest. He continued working on it until his death in 2004.