A return visit to what was then Rhodesia provided the research data for Carl's book "Jungle Gods," which was printed in several languages. The book follows the religious rites and customs of a single African tribe for a full year. It was during this period that Carl was able to spend much time with the native population and study in depth their way of life and rituals, probably never before witnessed by a white man. He is also author of "Jerry on Safari," a book for young people.