There are numerous web sites available with information about whiteflies that most search engines can locate.  The two sites listed below provide some great starting points.

The USDA Whitefly Knowledgebase contains numerous links to whitefly related sites, keys for identifying whiteflies, an extensive literature reference section, and other topics of related interests.

The AnswerSleuth web site links to over 100 different web sites about whiteflies.  Links at this web site sites range from very technical sites to those that are more for gardeners and homeowners.