What is the main difference between primary and secondary sources?

secondary involves the summary, collection and or synthesis of existing research, it also includes meta-analyses and literature reviews.

primary involves the collection of data that does not exist

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".

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