Manufacturers

International Rectifier

National Semiconductor 

WWW

SMPS.US

SMPS Reference Manual by OnSemi

Regulator Handbook by OnSemi

Power Supply Cookbook by Maxim

Here are some excellent online documents:

http://www.onsemi.com/pub/Collateral/SMPSRM-D.PDF

http://www.onsemi.com/pub/Collateral/AN920-D.PDF

http://www.semiconductors.philips.com/acrobat_download/applicationnotes/APPCHP2.pdf

http://www.ericsson.com/microe/tools/powermodules/powermodules.shtml

http://www.powerint.com/index.htm

http://www.cdncl.com/

http://henry.fbe.fh-darmstadt.de/smps_e/smps_e.asp

http://www.coremaster.com/appnotes.htm

http://www.eetasia.com/HOME.HTM

http://www.power-one.com/technical/articles/topo_e.pdf

http://www.st.com/stonline/products/promlit/pdf/sgsmps-0102.pdf

Power Electronics by Faz Rahman