Philosophy Pages
Philosophy Pages: Engels, Friedrich (1820 1895)
Brief entry provides links and a list of recommended reading for understanding Engels (1820-1895 CE) and his work.
Victorian Web
Brown University: Victorian Web: Karl Marx (1818 1883)
This site provides a detailed biography of Karl Marx. Links to related essays and articles are provided within The Victorian Web. This article is somewhat brief but provides good information on the subject.
Marxists Internet Archive
Encyclopedia of Marxism: Homepage
This site from the Marxists Internet Archive provides a detailed explanation including quotations from Engels and Marx, as well as explication. Links defining terms are helpful, as is the suggested further reading link.