The Chicago Manual of Style is a formal citation style that came about from (no suprise!) the University of Chicago. They describe the need for citations are such:
The purpose of source citations. Ethics, copyright laws, and courtesy to readers require authors to identify the sources of direct quotations or paraphrases and of any facts or opinions not generally known or easily checked. Conentions for documentation vary according to scholarly discipline, the preferences of publishers and authors, and the needs of a particular work. Regardless of the convention being followed, the primary criterion of any source citation is sufficient information either to lead readers directly to the sources consulted or, for materials that may not be readily available, to positively identify the sources used, whether these are published or unpublished, in printed or electronic form.
- University of Chicago Press, The Chicago Manual of Style (Chicago: University of Chicago Press, 2010), 655.
There are many links out there to the Chiago Manual of Style, but the latest and greatest edition to be had is the 16th edition, available for free at the RIS Help Desk in Blackell Library. Just walk in and and ask for it, and it is yours for in-library use as long as you need it! However if you are unable to get yourself tot he library to get hold of this item in person, there is one main link we recoomend that you can consult for online help.....