IEEE (Institute of Electrical and Electronics Engineers) Style is widely used in engineering, computer science, and other technical fields. IEEE [pronounced I-triple-E] style is a numbered reference style, using bracketed numbers , , and so on in the text. In the Reference List, numbered sources are listed in the order they appear in the text.
A DOI is a unique, permanent locator for online materials.They are usually found at the top of an article or with the other citation information -- look for the letters "doi" followed by an alphanumeric sequence beginning with 10. Many older articles may not have a DOI.