Although style guides vary in usage rules for numbered in-text citations, the standard convention is to name the authors rather than refer to them by reference number. Compare the following examples:
- Avoid: According to , . . .
- Correct: According to Jenkins et al. , . . . :
- Avoid: . . . is described in 
- Correct: . . . . is described in a study by Rowe et al. .
However, we’ve all heard the idiom “There is an exception to every rule.” Particularly in the fields of computer science and engineering, some journals, such as those published by the Institute of Electrical and Electronics Engineers (IEEE), do allow reference numbers to stand-in for words, and in fact, require this style.
In the 2019 IEEE Editorial Style Manual for Authors, the requirement is explained as follows: “The author’s name should not be included in a text reference with a number (i.e., ‘In Smith ’) and should be changed to ‘in ’ except in such cases where the author’s name is integral to the understanding of the sentence (e.g., ‘Smith  reduced calculated time …’)” (p. 12).
Here are some additional examples showing IEEE citation style:
- For more information, see , , .
- As aforementioned , this method has applications in . . .
- As shown in  and –, . . .
Do not begin your sentence with a reference number.
- Incorrect:  reports that . . .
- Correct: Yang et al.  report that . . .
For more information, visit the IEEE Editorial Style Manual for Authors
A helpful summary of the IEEE style can be found at Victoria University’s online Library Guide, “IEEE Referencing: Getting started with IEEE referencing”
Caution: Although IEEE style allows in-text citation numbers to be grammatically treated as nouns, many reference styles do not allow this usage.
Bottom line: Consult the author instructions for your target journal to determine the journal’s style for in-text citations.