1. GoPubMed: exploring PubMed with the Gene Ontology;Andreas Doms;Nucleic acids research,2005
2. PubNet: a flexible system for visualizing literature derived networks;Shawn Douglas;Genome biology,2005
3. HubMed: a web-based biomedical literature search interface;Alfred Eaton;Nucleic acids research,2006
4. Comparison of PubMed, Scopus, Web of Science, and Google Scholar: strengths and weaknesses;Matthew Falagas;The Faseb journal,2008