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Daily Bible Study the Ten Plagues
This is an excellent site to help with research on the Ten Plagues in the book of Exodus. It describes the situation in Egypt that the time and gives Biblical references for each plague.
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Ohr Somayach International: The Ten Plagues
Ohr Somayach International provides an introduction to the Ten Plagues. Recently an artifact was found that parallels the Bible's account of the Ten Plagues. Scroll down the site and you can read the similiarities.