After you destroy Sollozzo's warehouse in Special Delivery you are given the task of bombing his four drug fronts. Unlike compounds, you will only need one bomb for each front. Also note that each front contains hidden moneybags, like in the main missions. Unlike the missions, however, the game doesn't record whether you've collected these moneybags, but you might as well collect them and add to your bankroll.
From StrategyWiki, the video game walkthrough and strategy guide wiki