What sources of papers are supported?
The system currently supports: ACL Anthology, AIP Scitation, Amazon, Amazon, American Chem. Soc. Publications, American Geophysical Union, American Meteorological Society Journals, Annual Reviews, Anthrosource, Association for Computing Machinery (ACM) portal, Association for Computing Machinery (ACM) portal, BMJ, BioMed Central, Blackwell Synergy, Cambridge University Press, Chicago Journals, CiteSeer, CiteSeerX Alpha, Cryptology ePrint Archive, DBLP, Daum, EdITLib, Education Resources Information Center, HighWire, IEEE Digital Library, IEEE Explore, IUCr, IWA Publishing Online, Ingenta, IngentaConnect, IoP Electronic Journals, JSTOR, Journal of Machine Learning Research, Mary Ann Liebert, MathSciNet, MetaPress, NASA Astrophysics Data System, National Bureau of Economic Research, Nature, Open Repository, Optical Society of America, PLoS Biology, Physical Review Online Archive, Pion, Project MUSE, PsyCONTENT, PubMed, PubMed Central, Royal Society, Royal Society of Chemistry, Science, S