Embodiments are described for a system for integrating expert sources of knowledge into a general search service. The method can include a general search engine interface to receive a search query with at least one search term from a user. An expert knowledge engine can enable retrieval of expert information and analyzes. A predictive model module can be used to determine a probability that an expert knowledge engine may provide a valuable response to the query. The search query can be routed to the expert knowledge engine based on a cost-benefit analysis. A query reformulation module can reformulate a query for use by the expert knowledge engine. A display module can be employed to combine the expert search results with other search results.