A friend is developing a historical timeline of WWII information. 
What is his requirements to document information he takes off other
websites- is it similar to print references (books, articles, etc) for
footnote crediting?

Hi! Thanks for the question.

Here are the footnote formats for websites you can use according to
different style guides. The syle guides are Modern Language
Association, Chicago Manual of Style, and the Scientific Literature
Citation Style. Aside from websites, it also has rules for citing
books, encyclopedia and database sources.

"Citation Citation Citation"
http://monet.mercersburg.edu/library/citations.html

Search terms used:  
citing websites footnotes

I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.
                             
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Easterangel-ga                              
Google Answers Researcher