New York City-based Havas Advertising’s Euro RSCG Worldwide division purchased Middleberg + Associates, also New York City, one of the fastest growing public relations agencies. Founder Don Middleberg will remain ceo of what will now be called Middleberg Euro RSCG. With billings of more than $22 million, the p.r. firm’s clients include CMGI, Sesame Workshop, and United Airlines.