This document discusses bibliometric-enhanced retrieval models for big scholarly information systems. It describes projects that applied bibliometric analysis techniques like citation analysis, co-occurrence analysis of controlled vocabularies, and analysis of author networks to develop value-added information retrieval services. These services include a search term recommender, "Bradfordizing" to rank results by core journals, and ranking papers by author centrality. The services were evaluated on their ability to improve retrieval precision and provide additional relevant results compared to traditional models. While precision was mixed, the services were found to provide new relevant documents not found through other methods.