Managing bibliography

Reference management softwares
JabRef is a java - OS independent - free software. It works directly with .bib files and allows one to search, sort, manipulate bibitems in an efficient way. You can download refs from arXiv by providing the numbers or directly copy-paste bibitems from webpages.

More reference management softwares can be found on the net.

Database

 * arXiv
 * ADS
 * Scholar Google