When talking about or referring to someone who could either be a male or a female, I usually write it as (s)he but I have also seen usage like he/she, which also seems correct to me.
I use (s)he mostly because I find it shorter (fewer keystrokes). Are both (s)he and *he/she” correct? Any references are welcome.
And could s/he also be used?
Take a big chunk of your text and print it out in a few different ways, read it, and see which you prefer. There isn’t a correct answer here.
Do pay attention to the visual – if you’re using the phrase often enough, then your page may look like a mess of /’s or ()’s from a distance.
Personally, I’m biased towards “they” or rewriting so that your pronouns refer to an example person with a defined gender. This doesn’t leave anyone out, especially folks who find neither “he” nor “she” to be a good fit for their gender. (Plus it avoids the aforementioned symbol overload.)