If you are searching for papers or publications, here are some usefull links:

• http://citeseer.nj.nec.com/cs
• http://www.sciencedirect.com
• http://www.acm.org/dl
• http://www.google.com

For psychology/perception papers:

• http://www.psycinfo.com/library/
• http://www.ncbi.nih.gov/entrez/query.fcgi