sci-napse is the fastest search engine for scientific papers. sci-napse covers over 170m+ papers and 48k+ journals. Just try sci-napse, you can quickly find the scientific paper exactly you want.
ZoteroBib is a free service that helps you build a bibliography instantly from any computer or device, without creating an account or installing any software.
Paperscape is a tool to visualise the arXiv, an open, online repository for scientific research papers. The Paperscape map currently includes all (non-withdrawn) papers from the arXiv and is updated daily