This question already has an answer here:
Suppose you are writing an academic paper. When referring to an author of a paper whose gender is unknown, what pronoun should you use? "He", "she", "he/she", "they", etc? Maybe you think this is a trivial question if you refer to the author only a few times. But what if you have to refer to the author 10 times or more?
Remark(Nov. 14, 2015) My question is different from the question with respect to the following points.
1) You are writing an academic paper.
2) You have to refer to the author of a paper whose gender is unknown 10 times or more.