New York--Embattled online advertising company DoubleClick Inc. announced it is to sell its European media sales business to DoubleClick rival Montabaur, a division of Germany-based AdLink Internet Media AG. The news comes soon after Barry Salzman, DoubleClick's media chief, quit. It also comes as some Wall Street analysts speculate that DoubleClick may leave the media business altogether. Over the past year, DoubleClick has aggressively invested in non-media businesses, including ad serving software development and list services. Financial details of the AdLink Internet Media deal were not available.