Online search engines for papers:

Use the Knisely book to additional search engines.

You may have to go to UCI or another 4 year school to get the actual papers if you do not want to have to pay for them.  Many journals will have you pay for an article if it has been published within the current year.  After the current year, many articles are available free of charge.

If you find papers that apply to your topic, you can always look at their references.

Here are some search engines that you may want to try:

Infotrac - go through the Saddleback webpage

Science Citation Index

Google Scholar: http://scholar.google.com/schhp?ie=UTF-8&oe=UTF-8&hl=en&tab=ws&q=

Stanford search site: http://highwire.stanford.edu/

Ingenta:  www.ingentaconnect.com

Proceedings of the National Academy of Sciences of the United States of America: http://www.pnas.org/

Pub Med: www.pubmed.gov