 Complete the following phrase:  At twenty-seven, Čengić left his career as a guitarist to devote himself to the study of sound engineering and became a record producer. During the late 1980s, he produced records of several Sarajevo-based bands and musicians, such as LaBanda, Bombarder, Major, Elvis J. Kurtović  His Meteors, and Milić Vukašinović. In 1990, he co-founded the Rasa Music Production, an independent record label that survived the 