Trouble with many pdf file that you have collected? These proposed softwares could be help you to manage numerous pdf file especially collected papers.
1. Quaneko (http://quaneko.sourceforge.net/). Applicable for many operating systems, such as: Window, Linux, and MacOS. This software will create a database interface which the data was inputed when you create a pdf file. It is also nica that it can directly give a link to the file. Not only pdf, it can be used for .txt and .doc also.
2. JabRef (http://jabref.sourceforge.net). Work in all operating systems similar above software. This software uses BibTeX, the standard LaTeX bibliography system.
3. Referencer (http://icculus.org/referencer/). This is only applicable for Gnome. It shows nice to browse the files in a folder.
