We present an efficient search approach for selecting all potentially relevant data sources for a conjunctive Semantic Web query. We use map ontologies to align heterogeneous domain ontologies. This allows us to select data sources that may be relevant to the query but generally do not describe their data directly in terms of the ontology of the query. The "Goal Node Search" algorithm is a significant improvement on our original source selection algorithm. The new algorithm allows a more expressive knowledge representation language to describe domain ontologies and it is about three times more efficient than the original source selection algorithm when performing similar tasks.